What do you girls like to talk about?

Ask her what she wants to talk about.

Girls like to talk about interests that we have sometimes how we feel about you we also like to talk about what we want.

Ask her about her interests, her family, school work..Stuff that's happend to you that day, always good to make her laugh

um just ask her what she likes

I suggest reading some daily news. Interesting ones, ones that people like to talk about. Learn some jokes and tell them when the situation arises. Hang out with friends more often and that by itself will be a source of a lot of cool stories to talk about.
More importantly listen to what they talk about and relate to them. Don't randomly start talking about a story that you read somewhere and just because it is funny. The stories are only funny if they are relevant to what you are talking about. I also noticed in your question that you are having difficulty articulating yourself. Reading anything will help you improve not only your knowledge but will help you keep your vocabulary up-to-date, thus help you articulate yourself better.