Just join games that say noob in them, or host your own.
This, and remember to name your game "newbies".
With the next patch player stats (basically how experienced they are) will be displayed in the lobby. Just look for games where the players have similar stats to yours. Playing in a game with more experienced players will not be fun for you because they will quickly find out that you are easy prey and focus on killing you.
There's no shame in joining "newbie" games in the beginning.