White plays 1.e4, Black answers 1…e5, and White is on move again. That alternation runs unbroken to the end of the game, and it starts with White because Article 1.1 of the FIDE Laws hands the first move to the player with the light-coloured pieces. There is no toss at the board and no way to pass, which is a rule with real consequences: see whether you can pass your turn.
8 
7 
2 
a 
b 
c 
d 
e f g h 1 How the colours get handed out
Two ways, depending on where you are playing.
In a tournament the pairing decides it. Swiss pairings try to give every player an equal number of Whites and to alternate them round by round, so nobody gets four blacks in a five-round weekend. You find out when the list goes up on the wall, and there is a page on how a Swiss tournament works if that is new.
In a friendly game the old method still works: one player takes a white pawn in one hand and a black pawn in the other, hides both behind their back, brings out two fists, and the opponent taps one. Whatever is inside, that is your colour. In a match of several games the colours alternate, which is why a match is normally scheduled over an even number of games.
Online, the server does it, and in a series of games against the same opponent it will swap you over.
What the first move is worth
About half a pawn, if you want it in those terms, and roughly 55 per cent in score across big collections of master games. That figure counts draws as half, so it does not mean White wins 55 per cent of the time. It means White wins a bit more often than Black and draws a lot.
The reason is a single tempo. White gets to put a pawn on e4 or d4 before Black does, and to develop a piece one move sooner, so White is the side setting the questions early on. Black’s whole opening task is to answer them without falling behind, which is why openings for Black are chosen for solidity rather than ambition.
At beginner level that half-pawn is invisible. What decides your games is whether you noticed the knight attacking your rook, and the first-move edge will not save a hanging piece. Worry about it around 2000. Until then, pick a first move you understand and play it every time: the best first move in chess gives the two sensible candidates, and the opening patterns show you what people do with them.
I have never lost a game because I had the black pieces. I have lost a good few because I had the black pieces and played the opening as though I had the white ones.