Welcome to the introductions forum! In here, you can make a topic introducing yourself.
These types of topics are meant to promote discussion about you - basically, just talk about yourself. Common topics may include who you are, why you're here, how you got into SMBX, where your username comes from, what your favorite food is, and stuff like that. Posts that just say "hi" aren't what the forum is for. In addition, replies that just say "Welcome to the forums." aren't what the forum is for either. The point of the forum is to talk, not just make meaningless posts.
In addition to the above rules, please do not create a thread if you're leaving the forum. If you want to leave the community for good, you'll be better off doing so silently - there's no reason to make a point of it in this forum. The best way to leave a community is by, well, leaving it. I've seen a lot of users making "leaving" posts and then coming back later, and that's pointless! Also, if you're going on vacation, you can feel free to make a topic about it in the Sandbox forum.