[How do you use your premium tier?]

I have had premium for about two months now, and I'm thinking it might be cheaper for me to just use my tier for the mainland to put my home on.

I don't know how to use it, and I've been searching the website for hours.

Where do I go to actually claim this tier?

How do I see what Land is available and where?

Sorry, this has probably been asked before and answered but I just can't seem to find the info.