we're similar, i hate losing. My best advice for someone just starting is to know their level which is what you're trying to do now...if i had any clue when i started i would have been way better off. Try newbie pugs, noona runs them but if you add me i'll invite you to the group.
Other than that i would try to avoid lobbies because sometimes they give people the wrong idea. i think it's important to find a group of guys you're friends with and just play in house pugs, eventually you will get some idea of which class you like and what your style is. UGC is good for starters, just make a team with said friends.
Links: www.ugcleague.com
http://steamcommunity.com/groups/na6v6newbiemix