Okay, I've been a member on this site for like a year already and I'm still dumbstruck about how to use tags, I mean how do you close them, when I submit a quote I do this {but I surround the b with , its just they want let me do it on here}

b Cartman  b : screw you guys, I'm going home 

and they say its wrong, they say I don't close my tags, can someone please explain this to me. thanks.