move the king on the rook or one square next to it. in 960 it is different for instance in one game i had a clear route to castle but since i had pieces on the queenside that were not out it didnt let me castle. just go in analysis and figure out what needs to be done to castle by a guess and check method
Castling on chess.com

You move your king mor than one space left or richt, and if you can castle, you will end up in a castled position
Hey, playing my very first Chess960 game on chess.com (correspondence type) and don't know how to castle. I mean, I understand the rule of castling if I were playing over the board, but how do I make the move online?
i'm in the same boat as you.

To those who are suggesting moving the King, in Chess960, there are positions where the King does not move during castling.
Hi guys,
I got an answer from technical support. The way you do castling in Chess960 is to first 'click' the king, then without moving it, 'click' the rook. It works nicely.
Watch your backrank.

If you experience a problem castling when there is only one square between the king and rook, click on the king and then on the rook.
http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=737

s_kid, the rules for castling are:
- Neither King nor Rook can have moved prior to castling
- There cannot be any pieces between the King and Rook
- The King cannot castle out of, through, or into check
- King and Rook must be on the same rank (basically, you can't castle with a pawn you've just promoted to a rook)

TheGrobe,
I know the rules on how to castle. I can do it on the board but unable to do it on the facebook application or the chess.com website. Even after satisfying the above parameters I am unable to castle. When I click on the king and then on the rook, nothing happens. I have tried different browers- IE, Mozilla, Google Chrome with no luck. I'll be glad if you can help.

The reason I posted the conditions for castling is because none of your active games here meet them.
Hey, playing my very first Chess960 game on chess.com (correspondence type) and don't know how to castle. I mean, I understand the rule of castling if I were playing over the board, but how do I make the move online?