The tensioner is on the other side of the engine.
There is a small shock absorber attached to the top of the engine, that shock absorber goes to the tensioner.

To adjust the tensioner you have to release the big bold that goes trough the tensioner first, then adjust with the long nut next to the steering fluid reservoir . Best to soak it first with penetrating oil.

There is a indicator on the front of the tensioner.
Set the indicator to the first mark when the tension is released, with full tension it should be at the 7th mark (if you tensioner is still OK, the rubber tensioning parts do wear out).

Rob