The nature of the Daily Puzzle is that you need to find the "best" moves, the ones that force a win: often a checkmate, but sometimes just an overwhelming material advantage.
"White to move" means it is White's turn to move and you need to make that "best" move. If you make any other move, it will say "Incorrect" and you will have "failed" the puzzle, although you can always try it again.
The Daily Puzzles normally consist of more than one move, so even if you find the "best" first move, the computer will move as Black and then it will be your turn, as White, to find the next move in the sequence.
Danny Rensch does a Daily Puzzle challenge where he explains that sometimes the Daily Puzzle is a little unforgiving, in that if it expects a checkamte in 2 moves, it doesn't care if you make a checkmate in 3 moves, it will still "fail" you, when in reality it doesn't really matter all that much.
Hope that helps!
In the daily puzzle what does it mean when it says white to move? And when i move it says invalid move