AnonymousGender,
Exactly WHAT about that person do you "like?" How did you end up "liking" him/her?
(Although you said that you ended up liking "them," I assume you're talking about one person; am I right?)
How much do you know about that other person? Is that person still available or taken? WHERE is that person?
Don't ignore your feelings. "Check" them; "test" them to see if they're real. You shouldn't tell the other person before you know for sure you're ready. And that person is just a faceless "name," then you'll definitely have to find out more.
A good question to ask yourself would be: "Am I ready? If such a person were to come to my parents to ask for me (or even come to me directly!) what would I say? And why would I say that?"
Be smart. You've got only ONE life to live. Make it awesome!