She said that she liked me, so I asked her out, she said she will think about it?

She may like you but I'm sure that she is thinking about how it will affect her life (her friends, social life, family, etc). Don't worry though, if she says that she likes you, then she'll probably say yes.

She probably wanted to "think about it" because she wants to ask her friends what she should say. She wants their approval. That's pretty much all I can think of if she told you that she liked you.

If she said she liked you that probably took a lot of courage to do so. I say don't worry about it. If she really likes you she'll say yes. Some girls like to keep guys waiting. I know it sounds horrible but that's girls. Sooo my advice is give her time. If she likes you she'll say yes.