If a girl says they like you, it could mean that they want to date you. But it doesn't have to. They could just like you as a friend. My suggestion is, progress further into the relationship and see how it goes. However, the key thing to not do is to never ask if you are in the friend zone. The best advice would be to not even ask her to be your girlfriend. Believe me, I've done that so many times, and not one of them has turned into a date. Instead, look for signs that say she is interested. Really, the only sure sign that tells you that you're in a relationship is if you've already kissed each other (this strategy works ALMOST all the time), unless it's in a "friendly" setting.
Just remember that the best relationships start with two people as friends; hence the terms boyfriend and girlfriend. And one last note: Appearance isn't everything. I learned that one the hard way myself.