I'm a senior in my last days of highschool and i've never had a girlfriend not one and it's not because i haven't tried. so i was thinking why not date an under classmen just to get a feel for what a relationship is like. it probobly won't happen because i screw myself over somehow and there is no way to help myself.

Besides, assuming that you were looking at dating any freshman as opposed to any underclassmen, I would be uncomfortable with the age gap. Yes, I know that depending on how old you are that you could be dating someone two chronological years younger. But being that young, the gap of three years in school would skeeve me out.
DISCLAIMER: I am actually a pretty big proponent of dating outside of your grade and/or school in high school. I am a very recent high school graduate who is dating a sixteen year-old who just finished his sophomore year. However, we have a relationship that is very strong and that developed for reasons aside from me wanting dating experience.