so how do you create forums?

If you mean like Questions about Scratch, Bugs & Glitches etc, you can't do that. Only Scratch Team members can.
If you mean topics, you just did!

I mean one for a game or something

bun-bun2013 wrote:

I mean one for a game or something

If you want to advertise a game you made, you can do that in the Show and Tell forum by creating a topic just like you did this one.
If you want to create a discussion for a video game outside of Scratch, you can create a topic in the Things I'm Reading and Playing forum. But before you do that, make sure you check the directory to make sure a topic for that game doesn't already exist.