If you click the moves tab on top of the chat box in turnbased (which you seem to be rated by), there's a 'flip board' button. But upon starting a game, the board should automatically set your side on bottom unless you've clicked the 'always show white on bottom' box in your settings (http://www.chess.com/home/echess_settings.html)
Is it possible to flip the board on chess.com when you are playing black? It's hard for me to look at my moves when I'm black and the board has black on top. Thanks.