Just as General Charles said, if you go to Skyrim roleplaying and click in stickies it's all in there. But if you want I'll summarize it for you:
When somebody wants to creat an RP, they will make two threads. One is the actual RP while the other is to recruit participants. You can tell which one's which one by the title.
When you want to participate Ina an RP, look for the recruiting thread and ask of there still are vacancies. You'll have to send a CC(character chard), which is where you explain your character(looks, personality, weapons...), note that no one wants overpowered characters.
Also, check the date on this things, if they're from further than two months, it's either dead or closed.
Usually the rules for an RP are displayed on the threat.
If you want to enter an RP without bothering for being accepted or the like, go to OPEN RP, those are completely open RPs that take place in one single place.
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