Gaining

Well, you have a profile, pics, and a board post, so I think you have figured out the mechanics of most of site just fine. Everything else is really just communicating with people (on the boards, in the shoutbox over on the side, by leaving comments on their pics or stories, or in the chat room).

Just dive in and you should be fine

PS: lucky hubby!

If the hubby likes it and you like it, then it's a no-brainer! You will also find great tips and encouragement here. Welcome!

Sounds like you are in a nice relationship conducive to gaining I say go for it.
I have a thing for fat guys and find them very attractive too.