How do I create a topic conversation?

I was sitting on a table with two girls and they are highly interest in me. However, it get awkward when I ran out of things to say. Then one girl have to create a topic conversation for all of us. Again I still don´t know what to say and every time I think of something, its black. I asked the girl why are you bored and she respond ¨Because I don´t make any conversation¨

How do I create a conversation alot?