Hi there and welcome to Iwaku.
I'm Kitti and it's good to meet you.
You look like you might be new, so let me provide you a little help from the getgo to help you hit the ground running!
This is where you can sign up for the roleplays found in Modern, Scifi, Fantasy, and sometimes Mature. Generally, they will have you post a character sheet in their thread, a new sheet for each roleplay! You can also start signups for a roleplay of your own here.
This is where you can find jump in games, which typically have no sign up thread. You just start posting!
If you have any questions or need any help, feel free to ask!