On the client, send the player's position to the server with send_skill(). The server should then spread that player's position to all the other players.

Trouble is, when the server receives that player's position, it will send it right back to the client who originally sent it. This will overwrite any movements the client has made. To fix this, save the client's position into an array handled on the client side. When the client receives his old position from the server, just revert the client's position to the one saved just before the client's position was sent.

It's tricky, but if you follow the logic of it then it should make sense.