I don't know how to castle in chess in "chess.com"

Can someone teach me how to castle in "chess.com"? I know how to castle in chess in real chess board but I don't know how to castle in  "chess.com". This is the instruction from this site and I don't know how to move.

it must be that king's very first move
it must be that rook's very first move
there cannot be any pieces between the king and rook to move
the king may not be in check or pass through check
Notice that when you castle one direction the king is closer to the side of the board. That is called castling "kingside". Castling to the other side, through where the queen sat, is called castling "queenside". Regardless of which side, the king always moves only two squares when castling.

That seems completely clear . When those conditions all exist, you can move your king two squares to the right( or to the left if you are castling that way). The rook will move automatically.

If you’re new to chess, castling can look like an illegal move at first because two pieces move at the same time. But this is a legal and very important move in chess! Watch this free lesson on castling, or read on below:

Castling is the only time in chess that two pieces can move at once, and the only time a piece other than the knight can move over another piece. The king moves two spaces to the left or to the right, and the rook moves over and in front of the king, all in one move!



To castle, simply move the king two spaces to the left or right, OR move the king on top of the rook you want to castle with. The rook will jump across and to the other side of the king automatically!

You can’t castle any time you want to, though. Here are the rules for castling:

Your king can not have moved- Once your king moves, you can no longer castle, even if you move the king back to the starting square. Many strategies involve forcing the opponent’s king to move just for this reason.
Your rook can not have moved- If you move your rook, you can’t castle on that side anymore. Both the king and the rook you are castling with can’t have moved.
Your king can NOT be in check- Though castling often looks like an appealing escape, you can’t castle while you are in check! Once you are out of check, then you can castle. Unlike moving, being checked does not remove the ability to castle later.
Your king can not pass through check- If any square the king moves over or moves onto would put you in check, you can’t castle. You’ll have to get rid of that pesky attacking piece first!
Castling, Castle, Chess, How To Castle

White is not allowed to castle through the bishop's "check" on f1!

No pieces can be between the king and rook- All the spaces between the king and rook must be empty. This is part of why it’s so important to get your pieces out into the game as soon as possible!