Welcome to the realm Lenric 
Since you mentioned you’d like to learn about RP I’d recommend giving our guide to newcomers a read, it’s got all the basics laid out for you. I’ve linked it at the bottom of this reply.
Once you got the basics down you can start to design your character based on your interests and preferences, which may take a while of thinking, planning, and reading about the lore. Most people enjoy that character designing process a lot - if you get stuck, want some help with specific questions or just feel like discussing topics and making friends, we’re here for you on the forums and in-game.
I’d also recommend making a new forum topic once you feel prepared to start RPing, to introduce your character and describe what type of guild you’d like to join.
Not just so they can show you the ropes, but also to get that sense of community you wrote about.
It’s wonderful to spend time with people in RP on a recurring basis, where you create your stories together as part of your characters’ shared purpose.
(You could join a non-RP/social guild instead, of course, and simply participate in walk-up RP only. But I’d warmly recommend you try to find a RP guild to call home. It gives your guildies more reasons to want to interact with you and befriend you. And the RP guild will likely meet your drive to do game content as most also do dungeons and raids and social stuff together.)
This realm gives you a dazzling diversity of RP guilds to choose from, ranging from light-hearted to rather serious, with a broad or a niche guild concept, with loads of people or small and close-knit.
These guilds come in a whole range of flavours based on what kind of RP the players want to be doing, and where, and how.
Scheming evil magic users pretending to be merely scholars? Worgen fighting tooth and nail against the forsaken to reclaim Gilneas? A cheeky rogues-only guild that goes around thieving from strangers? The ongoing tension between cynical war veterans with PTSD who work side by side with innocent and optimistic new recruits?
Funny and silly Peon RP?
You name it, we got it.
Some guilds are strictly or loosely race-based, class-based, location-based, or part of a lore organisation. Others focus on a certain genre instead and take on a selection of races/classes or simply allow anyone to join. They may have a home-base. They may travel all over Azeroth and beyond as part of their adventures or missions.
By genre I mean: military, mercenary, diplomacy, adventure, criminal, townships, mercantile, scholarly/research, piracy, etc. If none of that directly appeals to you, don’t worry - with this many guilds about, there is something for everyone.
Hope this helps, Lenric! Again, welcome to Argent Dawn and on a final note, don’t worry too much about your English. Your post is clear and friendly and moreover, people here are generally quite forgiving and helpful.
Here’s that guide I mentioned: