One of my best friends in college was the Pennsylvania player of the year for high school football, and from him I learned a lot about how the college recruiting process works in football.
In the college recruiting process, it is common to make a highlight tape of you playing football, usually lasting several minutes. The tape is a compilation of you demonstrating athleticism and good plays that you make. You then send off that tape to dozens of colleges in an effort to get their attention.
It's also common to include "specs" (height, weight, 40 yard dash time, weightlifting numbers etc.) and a letter of why you would be a good recruit.
You will often get feedback from colleges who aren't interested in you so it is definitely worth reaching out. In some instances, if you are looking at Division I schools they would suggest that you look at smaller schools (DII or DIII) where you would have a better chance of being recruited.