My Brain is fogged: How do I move a networked object with user input

So I know how to do this, but for some reason for the last hour or two I can't put it back together in my head.

What I am wanting to do is have a user select the object and use the GUI to transform it with buttons in my GUI. What I am doing now is having it where the script attached to the buttons simply sends a message to the server to tell it to move the object then sync that objects new position for all players.

My question is how do I specify to the server which object I am talking about moving?

Also just another side question I will need later: Most of my private data messages are using custom messages and using their own message bases and such. Is there an easier way to tell the server to just move an object and sync it rather than making 4 message bases (To and From) the server with this data?

Thanks, Rotavele