On a new machine, make sure you are signed into the same Steam account as where your game was originally installed and you saved your save game to the Steam cloud.
Go to the Load Game and select the 'Cloud' tab. Here will be listed all your saves on the cloud. Select a save game and then the 'Load' button to load your save.
You must have an active Internet connection to use the Cloud Save Settings.
Edited by Neil Brock