Just play and you see your rating go up or down , depending how well you play.
Chess rating system

Glicko system sucks and is no good for on-line (or anything else) correspondence chess. Newcomers should have a provisional rating for 20+ games using the systems used on other web sites.
how can i know my rating?
Play some rated games, and a rating is automatically given to you.
I'm basicly "underrated" in chess.com because all I do is chess mentor/vote chess and forums and no live chess, but I'm overrated in the real world.
wow ppl
just play
ratings dont even matter
People do get obsessed with them, but they do tell us how well we are playing (which is an important feedback for improvement) and match players up (I like my rating to be "realistic" so I can get evenly matched games).
Usually the average Elo rating is 1200 so that's why chess.com starts you off with a 1200 blitz rating.
Download super 'Chess Rating' application for IOS devices
https://itunes.apple.com/us/app/chess-rating/id882338553?ls=1&mt=8