You should know this basic king versus pawn endgame below or you are unable to win when you are a pawn up. This is basic chess knowledge.
Make sure you get the opposition. In the opposition it must be Black's turn to move or the game is a draw.
In the position below you see the opposition (the kings are opposing each other) but it is White's turn to move. This is bad. You cannot win this way. Make sure that in this position it is Black who must move first. This can be done, but think for yourself.
Don't end up in a stalemate position like this below!
Black has to move, but can't, it is a stalemate, which is a draw. (half a point each)