There are two types rolling stock: locomotives and cars. Simply drag an item from the "Train" window onto a cell containg track. If you drop the train item on another train item that is already on a track, the items will be coupled automatically.
Train window
Moving train items
You can move a train item to another track cell by dragging it. Uncoupling, if needed, will occur automatically.
Deleting and uncoupling train items
The train item's contextual menu appears when you click on the item while holding the control key. With the help of this menu you can delete the selected car or the whole train, and you can uncouple cars from each other.
Reversing and turning a train
You can also reverse (change the direction of) or turn (change the orientation of) a train through the train contextual menu (click while holding the control key).
Locomotive camera
If there is more than one locomotive on the layout, you can also attach the camera to a specified locomotive using the train contextual menu.