Luke knew about the doors, both Ben and Leia had told him about their trips through them but he hadn't tried for himself as of yet. He'd been trying to get settled, find what he needed to keep Artoo powered up and thinking about his conversation wth Mara Jade. Maybe a trip through the doors was just what he needed to keep his mind off things that he couldn't quite understand.
"No, I haven't been through yet. I've heard about it, my friend and my sister have told me stuff but this is my first try. I'm Luke by the way, I haven't been here very long, maybe a week or two? I lose track of time."