To apply for Pell Grants for felons, go the FAFSA website and fill out the form online. This form will ask you information about your income and assets. It will also ask if you were convicted of possessing or selling illegal drugs.
Do not count convictions that were removed from your record when answering the question on the drug conviction. If you were convicted of drug possession and it's still on your record, you can complete a drug rehabilitation program after which you will be allowed to get Pell Grants for felons.
Take note of the SAR (Student Aid Report) after you have submitted the FAFSA. This summarizes the information you have submitted.