Hey Sturdy. Welcome to iwaku. It's nice to see someone so excited to learn how this all works. We all remembering being new and a little confused to start, too. If you have any questions, most of our members are really friendly, and the staff's JOB is to help you as best we can, so don't hesitate to ask! I'm not super sure what would be a good place for you to start, cause everyone tests out their limits in different ways, but Hana's right, the Murder Games tends to be a pretty steady series of roleplays to ease you in. You can also try throwing up a partner request in the 1x1's section if you think you might prefer to write with just one person at a time. As long as you say you're new, I'm sure anyone who comes to you will be really accommodating.
We do have a Newbie Care Package, which is where we assign newbies guides if they want it to help them both with roleplaying in general and with navigating the forum, and where you can ask for fancy little graphics pieces (of characters and rps and things) for your first two months here. :)