It is required by all prospective student-athletes to go through the NCAA Clearinghouse before you are eligible to play in any NCAA sport. The Clearinghouse is a way for the NCAA to make sure you have obtained the correct academic education standard. The NCAA calls it the being "Eligible".
Each prospective student-athlete must register and receive a clearinghouse number. To obtain the number, you must send in your transcripts and testing results (SAT and/or ACT), plus pay their registration fee (~$50 for US Students and ~$75 for International Students). This fee has increased over the years and will more than likely increase again. You can register as early as a Freshmen in High School (and is advisable if the fees are going up), but you should be looking to register no later than your Junior year in High School.
HERE is the link to the Clearinghouse.