I'm new, I just got my application approved today. I'm so confused I really want to build my house how do I do it? Do I have to pay for land or can I just go and travel far out and use open land? I've been looking on the FAQ and I couldn't find anything. I found stuff about how people found like small communities and stuff. They said they filled for an application. How do I do that?

You can either buy a plot in a town and build a house there, or go out and find unprotected land and build there and have it protected. You will have to go a LONG way from spawn to find unprotected land though.

How will I know if it is Protected? How do I protect it?

You have to make a pe to have a mod protect your land. There is a good guide on how to do this on the wiki. (link at the top of the page)