It is often said that your diet is responsible for 80% of the way you look and perform, because try as you might, you can't out work bad nutritional habits. As a powerlifter, you will need to eat like a horse to fuel your gym training, but you also want to be lean, so that you can be as strong as possible without carrying excess fat. 

The FAQ section on /r/Fitness has a section on Diet Details which covers pretty much everything you need to know about macros, micros, calories, and TDEE.