Hi friend
(Storm, be nice)
Just treat it like you're writing, a paragraph at a time. Know your character, and if you're ever confused, feel free to ask. That tends to happen a lot early on. Best way to learn is by doing.
As for open sign-ups, there always are. All of them are already started, but it's not hard to get into most of them. Here are my suggestions:
Rito's Beak: Domozilla's Wind Waker Pirate RP
Dark Disney: Characters go crazy at Disneyworld.
Dragons of Lythan: Kill the dragon lords that have conquered the continent of Lythan. Seems simple enough of a plot.
World War II RP: We take control of a platoon of multinational Allied soldiers during WWII. Just got started, think it's gonna be a blast!
Hyrule Dystopia: Fallout, but with the additions of Magitech and Zelda. An evil cult is seeking to take control of what's left of Hyrule after nuclear war. If you want an in to the mega-RP Storm mentioned, this is probably the best one.
Anime High School: We make fun of anime tropes and generally mess around in a Japanese high school where we have to write a play to stroke our teacher's ego.
Hyrule Civil War: Another good entrance to the storyline. Takes place during the Civil War that occured just before OoT. Plus, we literally just introduced a new group of NPCs, so if you wanna join up as one of them, your entrance is written in.
Sword Art Online: Exactly What you'd expect. A group of clearers in the world of SAO. Right now, we're on the second floor boss battle. We do expect to do a lot of killing off of old characters and adding of new ones though, so new players shouldn't be a problem.
Just join 1 or 2 of those, see how you like it. You should be able to ask anyone involved if you have any questions. And, if you want, we have both a Skype group and a Discord server we could invite you to.