Well, you've got enough to run the loco so long as you have the means to connect the transformer to the tracks.
Playmobil produced their own connector with two wires, one red and one blue. These ended in a piece which clipped to a rail between the sleepers. The other end was just bare wires and these attached to the red and blue connectors on the transfomer (which is also the controller of course in this case).
If you connect the red wire to the blue connector and the blue to the red, don't worry, you won't blow anything up, it will just mean that the train will run in the opposite direction to if you connected the wires red to red and blue to blue.
The black and white connectors on the transformer are used for powering such things as electric points and signals if you have them. Do not run the train off them.
You turn the knob on the transformer to the left or right to make the loco go forwards or backwards. Personally, I always connect the wires to the transformer so that turning the knob to the right makes the loco run forwards in an anti-clockwise direction. The knob also controls the locos speed - the further you turn the knob, the faster the loco runs.
The loco may not run smoothly to start with, so check that the backs of the wheels where they touch the track are clean and shiny and similarly with the "skates" between the wheels. The skates are bent up at each end - DO NOT STRAIGHTEN THEM!
For some idea of what rolling stock is available, this thread is useful:
https://www.playmofriends.com/forum/index.php?topic=16943.0None of these are items are still produced.