Welp, Yui did say a new member's entrance did surprise him. Seems like he was definitely correct.
Hello. Hola. Bonjour. Konichiwa. Ni-Hao. And other hello greetings in other languages. I'm YCM's Typecast Shonen Protagonist and resident RPer, Chaos Sonic. You can call me Chaos, Sonic, Chaos Sonic, etc. Honestly I'm not picky on the name, long as you don't call me late for dinner or anything else that sounds the same. Welcome to the forum (even though from the sounds of it, you've been here quite a bit annnnnnnd just now did this, but don't worry...we won't hold it against ya!), kick your shoes off and relax. Like everyone said, make sure to read the rules when you can and do what you can to have fun.
Also respect your Mod Team and try not to cause too much trouble 'round here. Keep all that in mind, you'll do perfectly fine here.
As for the knowledge of the YGO game itself, don't worry. Even though it is a YGO forum, most people don't have a grasp on all of the rules and whatnot (especially thanks to the Link Format).
Either way, hope you enjoy the stay at YCM.