Calm down, it's not that hard. Ever notice in the drop down time menu the word "custom"? Try clicking on it. A "rating options" button pops up. Click on it and enjoy. Oh, it needs to be at least + and - 25 or it probably won't work. And you probably want to read this:
https://support.chess.com/customer/portal/articles/1622811-how-are-seeks-matched-in-live-chess-
And maybe this:
http://www.chess.com/forum/view/livechess/new-logic-for-auto-pairing-and-seek-graph


I'm tired of getting penalized for not choosing to play far superior players. Either require us all to accept any game offered or allow us to select the ratings we wish to play. I used to be able to choose opponents within +10 and -50 point of myself. Now I'm stuck with +-200, and I'm penalized for not choosing games I likely can't win. Fix your site.