First we need to get the top solved. This is what we're trying to achieve in this section. Note that the sides should match the center side colors:

You can do this without any formulas but here are some to make things easier, match up your cube so that the piece you're trying to get into place is in one of these locations, then use the formula:

Once you have the cross, you can work on getting the corners into place. Once again, here are some formulas you can use, or you can just do it by yourself!