[@Srecius]

Hi! Welcome! Okay, so I don't know too much about the Arena, but I do know that they are usually 1x1, and are straight-up just fighting. For what you want, I would probably say to use Casual or Advanced, depending on how much depth of post you want. (Advanced would probably be better.) Also, Hiders aren't just usable in the Arena. You can use them anywhere. The code is: [hider] and to close it, put that, but with this: / in front of the word 'hider'. It looks like this:
[hider] Ta Da! [/hider] or, if you want to name it, put = after the first hider, and then what you want to name it, and then close the bracket. That bit of code looks like this: [hider=Hi! Welcome!]. If you have any more questions, feel free to ask. (Me or anyone who has been on a suitable amount of time!)
Good Luck,
~Arya