how can I insert a game? couse, I opnly get preview diagrams.

try clicking on the image and find the correct option

or else go to:

http://support.chess.com/

that I used the image, tryed Game or sequence of moves and then Start with a blank chessboard, I entered the moves and details and got a preview. That preview i tryed to insert but I got only a diagram.

For a full explanation of the Chess.com Diagram editor please see http://www.chess.com/article/view/how-to-use-the-chesscom-diagr