Develop your pieces, control the centre, get the king to safety. Good opening moves are often those that achieve several of those goals.
1.e4 is the most recommended starting move for beginners because it is one of the most straightforward initial opening moves. It contributes to all three goals: First, it stakes control in the center, by occupying the square e4 (making it impossible for an opposing pawn to move on it, for instance) and eyeing the square d5 in the opponent's half of the board. Second, it clears the e2-square, freeing a path for your king's bishop and the queen. Third, by clearing a way for the king's bishop, 1.e4 gets you one move closer to castling kingside.
There are a couple of additional rules of thumb often named, such as "knights before bishops", "castle quickly", "don't move pieces twice", "don't needlessly move pawns", "don't bring out your queen too early". They are all useful rules of thumb, but it's important to understand that they all also are just special cases of the three big ones; development, centre control and king safety.
"Knights before bishop" is a rather soft restriction - it exists simply because knights are going to want to go f3/f6 and c3/c6 respectively most of the time, while you have to watch your opponent a bit to figure out where a bishop might be placed best.
"Don't move your pieces twice" is about development again. Simply put, a move spent moving a piece a second time is a move you have not spent developing another piece. It can still be perfectly acceptable, beneficial even, to move a piece a second time before all the others are developed - if it disturbs the opponent's position, so they also have to insert a non-beneficial move they otherwise wouldn't have made, and achieves some sort of gain in the process. Those situations are rare, though. Unless you get something concrete in return, just continue your own development.
"Don't bring out your queen too early" also plays into this game of interfering with the opponent's development; simply put, the queen is too vulnerable a target. When a bishop attacks a knight, you can usually make another developing move that also protects the knight (if it isn't already protected), but when a piece other than a queen attacks a queen, unless there's crazy tactics involved, the queen will have to move. All openings that feature a queen move usually also feature a plan to bring the queen to relative safety if it does get attacked, or bring it to a good and safe square where that is not an issue to begin with.
"Castle quickly" is often named because beginners have a tendency to not consider king safety at all, and wantonly rip open the centre without sparing a thought for the poor monarch. Delaying castling can be perfectly fine, depending on the position, and beginners don't tend to end up in a lot of positions in which hiding behind an undisturbed line of castle pawns is a poor choice.
"Don't needlessly move pawns" has several reasonings behind it. One, pawns are not developed. Yes, you can push them down the board, but they don't become significantly more powerful that way, and more importantly they cannot move back. Some pawns are needed for defense; for instance a king needs a "wall" of pawns in front of him to stay safe from the intrusion of opposing pieces later in the game. The sturdiest that wall can be is if the pawns remain unmoved, for instance on f2, g2 and h2 (f7, g7, h7 respectively); this is simply because they can advance as needed, including to make sure that a file stays unopened.
There are many cases in which pawn moves other than those that free the bishops and the queen are perfectly good, even crucial opening moves: In basically all those cases, they are made to deny the opponent a crucial square. Without going into too much detail, in the 1.e4 c5 opening, the Sicilian, Black very often plays ...a6, simply to take control of the square b5, which White would otherwise commandeer for its pieces. Also, a pawn move might force an opposing piece to move again, in which case it's "free", whether it's beneficial is another question. In all of the cases, your king will want to have a pawn shield to hide behind, undisturbed if possible.
As a beginner, I'd encourage you to study your opening play, with a good player as coach if possible, and determine which moves you made follow sound opening strategy. At your level very few players have a clue what they're doing in the opening; you've got a leg up on them if you do, even if the results don't come around immediately!
So I have been playing chess online recently and losing. Allot. Basically because I dont know what to do in the beginning of the game. Once some pieces are out I can think ahead, but in the beginning I have no clue what to do. I pretty much just try and protect the middle of the board (not well). I know there are openings I should learn and things but its challenging to follow them under the circumstances often. So what should my thought process be in the beginning? What are my goals? And what are some good openings for beginners?