How to move tensioner

Me and my friend are trying to replace the serpentine belt on his 95 s10. It sounds stupid but we are pretty confused on how to rotate the tensioner. There is nowhere to put a ratchet in to rotate it. Please help

if no square hole for a ratchet, then there is a bolt head on the pulley....should eb a 15mm or something close.....put socket on ratchet, or you can use a wrench of same size.