Heh, haven't been online long?
You can't do much online without running into somebody calling you a dirty name, certainly don't let that stop you from trying MP. Play a fun game, be a good sport (by your own definition), and don't worry about it if somebody else gets aggravated at you. So long as you use a thimbleful of common sense and adhere to anything explicitly stated most people in this community are pretty tolerant, for the few that are loudly not there's a nice "ignore user" function of this forum.