Here's the link with all the info on nuitrition:
http://www.redearslider.com/index_nutrition.html
why don't you read through this and if you have specific questions then come back and we'll be glad to help.
If you're not sure how to measure the right amount of pellets to feed your turtle, here's a good thread with photos that might help. Every day, you're supposed to feed a turtle smaller than 4" long the amount of pellets that would fit in his head if his head were hollow. Bigger than 4", they should get a headfull of pellets every other day.
http://www.redearslider.com/forum/viewtopic.php?t=11368