Username vs Character
Hiya and welcome. I would say check out the Beginner Forum, but you still have received all the right answers here. As for your username, that is a name you choose for public roleplay forums such as this. Your character name is hat you want it to be in that game.
One thing that gets a lot of new players confused is there are loads of roleplay sights over the Web. The majority of these ve you make a different email for each character you make for that board. That was a tiresome nightmare to me.
On RPol you use only ONE username, only ONE email, and it is against site rules to have more than ONE login email or name. It can get you banned either temporarily until you work with the Site Admin and get it fixed. Same as give your REAL birthdate. Discrepancies will get you banned. Some bans are permanent, so make sure you have ONE username for site login, ONE email for the site login, and give your REAL life birthdate. Those are the rules. We have the best site moderators/Admin that will work with you as long as they can.
If you wish to play in ADULT games then from the first time you signed up to RPol and gave your username, site email, and real age there is a one time two week wait. After that, you are cleared for all ADULT games if you are 18 or older.
Now, as many have explained, you find a game you might like, and you click the 'request to join' words on that game's menu. This will give you a PM to the owner/GM of that game. This is where you present your character bio and work with the GM who when happy with the character will put you in that game as THAT character, or you may have more than one character to a game that you wish to present and play. GMs have different rule sets, so they are all unique to that game. But the characters you create for that game are not what you play in the next game, you choose if you want to play in one or more games. EACH game, you have to go through the Request to Join (RTJ) to take you to the PM for that game. You can play your character in more than one game if the GM allows it. Some have rules about that and as I said they all are different per game. Note that if you leave a game, your character belongs to that game, and it is up to the GM what to do with it. NEVER leave without telling the GM you are leaving. The character staying in game is an RPol site rule, and it is the Game Owner (GM) to decide what to do.
I do hope you find what you are looking for and there are thousands of games her, literally, something for everyone. Everything from System Games to creative writing Freeform!
I know that all those above have helped tremendously, and I hope I have too. Enjoy RPol it is the best on the Web, at least I think so, and I have played and owned other sites.
RPol Admin/Moderators can be reached through Rmail at any time, so be sure to have your Rmail turned on. There is a Wanted Players thread that you can put what you are looking for in a game. There is the Wanted Players that have many games listed, but the search feature there and on the Main Screen at the bottom are great tools to use to find what you are looking for. In a player post under their pic/avatar, there is the option to click on them to Rmail them to discuss their games.