Excel 2007 : Finding percentages?

I'm currently working on a little project to help me track of the protein/carbs/fat in the foods I eat. I have all my dropdown lists working and everything it totalling and changing like it's supposed to so I decided today that it would be nice to take the total p/c/f totals and in the cell below each, show what percentage it represents. For example, one iteration of the diet I'm on is 50% protein 30% carbs 20% fat and I was hoping to add the percentages below the totals to help keep me aware of how close I am to what I need to be.

The problem I'm running into is that I'm very new to excel and am still fumbling my way around tutorials. It seems that I need to get a total for the 3 cells then calculate the percent for each cell. At the moment my "totals" are in C15/D15/E15. Is there a way I can calculate the percentage that, say, C15 is of the 3 cells and display it below in C16 without too much fuss? Thank you very much.


Edit: Sorry to bother you guys, I sorted it out