Hey there! So, a few tidbits on the roleplay section of this site. First there's "fun" and "serious" RP. Fun is more laxed. Single sentence responses are fine, no word minimums, etc. You can have choppy sentences and still get by. Serious however does expect more formal writing styles, and usually have more rules stipulated by the GM (Game master, typically the person who created the post) beyond the basics. There's some pinned guides depending on whether you want to hop in "fun" or "serious." I'm more of a person who hangs out in the serious RP.
As for the basics, here's a few that apply across the board.
No godmodding/powerplay. This is essentially forcing actions on other characters that aren't your own. For example, your character is in a fistfight with another character. You can throw the punch, but it's up to your opponent on whether or not that punch lands, and how much damage it does. You can say "Bob throws a punch with the force of a train" to give a better guide to the other player on how much force is going into that punch. The reason this rule is in place is because players typically don't like it if you break their leg and throw them in the dumpster without them having any say or counter.
No metagming. This is using information you have OOC (Out of character) IC (In character). For example, two characters are having a private conversation. You, the player, know this. However your character does not. They should not act on information they do not know.
In most cases, no overpowered characters. This depends on the setting, but if everyone has special powers such as breathing fire, or the ability fly, and yours is the ability to literally detonate buildings with a mere thought, there's an issue. That or just being immune to all damage, even if a nuke was dropped on your head. (And yes, I have met those people/characters.)
There's probably some other stuff I forgot, and these are just the basics. You'll learn more as you go. OH, and one crucial piece of advice. Follow TFF rules. Nothing 13+. Don't describe excessive gore/violence/blood. No sexual themes, etc. So for your black market surgeon, probably best not to describe the intricacies of how bloody and invasive actual surgeries are.
If you're feeling confident, there's some open RPs that you can hop in. The Snack Den, though the two there are speedposters, so you might not be able to keep up unless you're on for most of the day. Galactic Society is slower paced with a proper GM, but it's sorta halfway between fun and serious. If you're not feeling confident, we can always do a "training grounds" RP, basically a quick RP to get the basics down.
If you have any specific questions, then please, ask away.
