For black I like the Caro Kann but tbh I don't really even know how to play it I just know the first few moves
what opening should i learn? (750 elo)
None. Just develop your pieces fast and castle. That is enough at 750 elo. Instead, spend your learning time practicing tactics. Also concentrate on a proper thought process every move and look at threats, possible checks and captures, and considers opponents response and ideas not just your own. That is why 750 players win or lose, not the opening.

@artodefeat makes a good point the opening does not really matter as long as you do the basic principles like developing your pieces and stuff at that level

I agree with @artofdefeat, openings doesn't matter on your level. Instead, develop your pieces and follow opening principals.

@Marie-AnneLiz Openings doesn't matter on that level. Instead, they should just focus on opening principals. Above 1800+, openings would come handy. Though learning openings is not a problem, but studying it throughly is something I don't recommend. Well, of course I am not referring to you as you are higher rated.

@Rimuru If someone wants to learn openings, let them learn openings. I would recommend Réti Opening for white and Caro-Kann Defense for black.

@KieferSmith In the end, it is their decision to choose what they prefer. However, what I stated is from my experience, and other experts experience as well.
everyone who says opening dont matter, i dont understand this, im 1000 and i lose all my games in the openings cause i know next to none, dudes are blasting out theory moves all the way to endgame, top engine lines, 80+ accuracy couple a mistakes and inaccuracies a game, what are you on about opening dont matter ?

reti develops a knight on move one, controls two center squares on move one, and since it's not as common as other openings, many people aren't prepared to face it.

No, you dont need openings. Just develop your pieces, control the center, and castle...
Well, that is what an opening is!!!
The problem with playing e5 is that you are going to let white setup how they want. Also many, many lines to know. So would be better to play something else. The sicilian is good. However at your level people aren't going to play against it for the most part. So you will need to adapt a bit.
With that said, go on youtube, and watch some opening videos. Try them all out. You will gravitate towards one or the other.

everyone who says opening dont matter, i dont understand this, im 1000 and i lose all my games in the openings cause i know next to none, dudes are blasting out theory moves all the way to endgame, top engine lines, 80+ accuracy couple a mistakes and inaccuracies a game, what are you on about opening dont matter ?
That's literally all of our points. You should just follow opening principals instead of learning and studying openings throughly as they will resolve those problems you have in the opening. Also, one piece of advice, focus to not blunder your pieces or miss a piece hanged by your opponent. You can climb to 1500 with that.
everyone who says opening dont matter, i dont understand this, im 1000 and i lose all my games in the openings cause i know next to none, dudes are blasting out theory moves all the way to endgame, top engine lines, 80+ accuracy couple a mistakes and inaccuracies a game, what are you on about opening dont matter ?
I looked at the last 3 games you lost, and as expected you lost solely because of blunders. At the 1000 level folks vary very very quickly from book openings, rending what you've studied useless. Whereas practicing tactics and a proper move process addresses why your actually losing. This is even more so at 750. At 1000, it maybe is a good idea to start studying a few limited opening situations, such as what happens if black tries to keep the pawn in queen's gambit. Although you can get most of that done by working with the engine after a loss.
everyone who says opening dont matter, i dont understand this, im 1000 and i lose all my games in the openings cause i know next to none, dudes are blasting out theory moves all the way to endgame, top engine lines, 80+ accuracy couple a mistakes and inaccuracies a game, what are you on about opening dont matter ?
That's literally all of our points. You should just follow opening principals instead of learning and studying openings throughly as they will resolve those problems you have in the opening. Also, one piece of advice, focus to not blunder your pieces or miss a piece hanged by your opponent. You can climb to 1500 with that.
1500 is too much of a stretch. But he could easily get to 1200 with really decent tatic reconigion and one move blunders.

everyone who says opening dont matter, i dont understand this, im 1000 and i lose all my games in the openings cause i know next to none, dudes are blasting out theory moves all the way to endgame, top engine lines, 80+ accuracy couple a mistakes and inaccuracies a game, what are you on about opening dont matter ?
all you need is opening principles and the ability to see opening traps
knights before bishops, center control, king safety...
I have 6~ moves of prep for white/black and look at where that took me

A great opening repertoire for you is this.
For white, play the Four Knights. It’s simple, principled, and is very simple in theory, avoiding too many complicated lines. A great line for a 750-rated player.
It’s simple, principled, and although it does have theory, you don’t actually have to learn it because of how simple it is.
Another great option is the Scotch.
This is only one line, the Scotch is a little bit more theory-heavy and you have to know your stuff- but if you get past that, the Scotch is a great opening and will get you many wins. Probably my second favorite e4 opening for white behind the Ruy Lopez.
The reason I don’t really like the Italian or the Ruy Lopez at your level is because they’re actually very deep rabbit holes that can get you in loads of theory that isn’t really necessary for a 750 rated player. You should focus on the middlegame and the endgame, don’t think too much about openings.
For black, a great opening to avoid theory is the Caro-Kann.
These aren’t the mainlines for each variation. These are GothamChess’s recommendations, which I usually find dubious, but his Caro-Kann recommendations are actually pretty useful for someone who’s looking for a solid position without having to learn too much theory. The mainlines are these, which hold a lot of theory:
Against d4, I love the Nimzo-Indian and the QGD.
Simple, straightforward positions.
i mostly play as white the italian and as black i play the scillian