An online friend asked me out and I said no. Need reassurance.

So I (22M) am a single fella and I'm not used to be flirted with nor asked out. I was the type of guy not to get any girls as I was largely unnoticed.

One of my online friends who I've been talking to, "Ana" asked me out. I didn't know what to say, so I said "Sorry, no."

I felt really bad. In reality, I did want to be asked out, but I have no idea what to say or how to be a good boyfriend. How do I ask her out without being awkward??