Solving the first face of the Rubik's Cube is relatively easy because there are not too many solved pieces that you can mess up.
Spend some time playing with the puzzle and try to do this without reading further this page.
We already know that the center pieces are fixed and they define the color of each face. This is why we have to solve the white edges according to the color of the center piecess as illustrated above.
Solving the white edges is intuitive and quite easy because at this stage there are no solved pieces that we can break. In most cases you can just simply rotate each piece where they are supposed to be.
Apply this short algorithm when the piece is in the right spot (FU edge), but it's oriented wrong.
Do this when you can't simply just turn the front edge to its spot with a double front rotation because it would be oriented wrong.
The algorithm to solve the white edge when it's oriented wrong in the middle layer.
The white edges are solved and we have to fix the white corners to complete the first face.
This is another easy stage where you shouldn't memorize any algorithm just follow your instincts.
Here's an easy trick you can always apply if you have difficulties solving the white corners by yourself. You just have to memorize a short algorithm and repeat it until the piece is solved:
Bring the corner below the spot where it belongs (Front-Right-Down position highlighted with grey) and repeat the algorithm above until the white corner pops into its place oriented correctly. This algorithm sends the piece back and forth between the spots marked with dark, always changing the orientation.
This trick always works but it requires too many unnecessary steps. Here are the shortcuts: