Welcome to the board. I normally go and look at what other quilters have done on Google or Pinterest.
https://www.google.com/search?q=Foot...ih=614#imgrc=_
One of them is from McCall's Quick Quilt magazine and another seems to be an actual football panel a field. Real cute and simple
http://www.creativequiltkits.com/foo...ics-15268.html
Good Luck !!