First you need to find the middle piece you want to start with I’ll be using white.
Find an edge piece and match the side with the middle in this case I matched red with the red middle and put it by the white
Again match the middle with its center and match the white.
Finish the final two white edges you should end up with a cross.
Find the two colors on the corner and that’s where that piece should go.
Do the same with all the corners until you are finished.
Finally you should have the entire white side with the matching centers.