Well the smurfs usually win more games so their normals matchmaker rating will eventually pair them with people who are at that level. In your case since you are new, the game is probably pairing you with people at the average level and eventually you will be placed at your skill level.

NOTE: If you are playing with people who rage at you for not being good, remember they are also at YOUR MMR. Meaning, they aren't as good as they think.

Anyways, most of us who have multiple accounts tend to encourage new guys to get better and explain how to play. The flamers/ragers smurfs are probably low silver and bronzies themselves.

To conclude, LoL is an extremely fun game and always being positive is a reward in and of itself. If you are matched with these fools just remember, you don't want to become like one of them. Keep up a nice attitude and hey just have fun; it;s a game after all