Auxiliary belts tensioners?

Hi guys, just taken ownership of my late father's 1.3 Si & wondered if anyone has a step by step guide to changing these two belts?
The car has AC & PS. Am I right in thinking you have to losen the idler tensioner nut, then adjust tensioner bolt for the ALT/PAS larger belt? Also no idler pulley on water pump, power steering side for small belt, just PS pump works as the tensioner, but what bolts should loosened on this before adjustment bolt?

Thank you