How do you swap the king and the rook on this game?

How do you swap the king and the rook on this game? I guess i'm doin it wrong or something because it just goes back to where it started

Are you referring to "castling?" If so, take a moment to look at your game. Has the king moved? Has the rook you wish to castle with moved? Are there any pieces between the rook or the king? If you answered "yes" to any of these questions, then you CANNOT castle. If all of the answers are "no," then let us determine whether or not you are trying to castle correctly: in order to castle, you must move the king two spaces toward the rook you wish to castle it with. It should work under all of these conditions.

If not, perhaps you should state this in your post so that it may be looked into further, along with your operating system and browser type.

Also note you cannot castle if the king is in check, the square he passes through is under attack, or if he would end up in check on his landing square.

I am not able to do castling.

There has been a recent change for standard chess. From now on, you can't click on the king and then click on the rook to castle. You have to move the king of two squares towards the rook (by clicking or dragging).