Most Helpful Guy
Forget about it. No one will care. There will be plenty of guys who didn't date in high school either. First kisses can be awkward regardless of how many other people you've kissed. As far as hooking up, don't do anything that makes you uncomfortable. A guy who pressures you is not a guy worth having. Before you become sexually active, get on some form of contraception, and make sure the guy uses a condom.
Most Helpful Girl
Nope. It won't be a problem at all. If it is, it's because of the guys you are picking up. Don't go for a hoe. My sister never dated/kissed anyone in HS and now she has two guys that are super into her going after her. Just be yourself. Join clubs and open up to people. Get out of your comfort zone.