How do I improve my opening?

My rating vs pretty good in live chess.
2000+ in blitz - play mostly
1550+ in rapid and bullet - don't play these formats much

My rapid rating may seem low, but the thing is I rarely play rapid. And I've beaten 1800-1900 rated players several times whilst having a continuous advantage. 

I'm good at middlegame and endgame, but in case of opening, I kinda suck

This has cost me severely, as I lost tournaments due to opening disadvantages.

So, how do I improve these?

I also want to know

study book moves 

can you give me link to this website?

https://aimchess.com/home

thanks

Just go to analysis and explorer and test all moves and see how to will play out until mate or if you see that you can’t keep your good advantage and play yourself and if you can’t keep your advantage then find a line that is for you, keep in mind we are finding playble for your level positions from the opening that you have a clear plan in the middlegame and endgame and if you don’t have that throw that out the window and find a line that avoids it while going into your prep and keeping it a playable position that you already have and if you can’t do your prep and avoid that line at the same time which is almost impossible then I suggest study openings that are more complex as high level KID or equal to the level of high level KID or each variation of the Sicilian and see all the lines with explanation from a titled player like @DanielleNaroditzsky(sorry if this is wrong, I forgot) and try to play it to remember that plan as you go on and get used to the pawn structures and piece positioning and if you know that, but not the position you were first struggling on then there will be an opening that will satisfy what you want.

I can put this in my blog too. Thx for the idea of me typing an essay. Don’t worry, I like making essays.

Go here in this blog called Chess Tips, Annotated Games, And Openings and check what you may be looking for and I’ll be updating this when I get the chance to. It may say unfinished, but that’s just a technical issue. Read this only for those people who know I am on ios I managed to make this because in a club I found a blog link and I clicked and I found the option to make a blog.

https://www.chess.com/blog/Jozonthe195/chess-tips-annotated-games-and-openings-unfinished

Thx again :)

Chess tips no. 16

https://www.chess.com/blog/Jozonthe195/chess-tips-annotated-games-and-openings-unfinish

Forgot to mention I added bullet points too