Essential part of becoming a Sport Pilot and achieving a Sport Pilot certification is to pass a written test.
There are some good self-study courses available or you may take a ground school course at a local flight school or community college.
As a prerequisite of taking the written test, you must have written proof of having completed ground instruction and the provider of the instruction must be certified.
Check out the self-directed Learn To Fly Airplane LSA online pilot course offered by Paul Hamilton’s Sport Aviation Center.