? changing belt on 93 S-10?

I need help. Can anyone out there give me the trick to loosen the belt on a 93 S-10. Normally you can find a tention bolt. I cannot find anything. I do see something that looks as if i need a Star bit to loosen. Is that it? Help please.

Is it a 4.3 V6?
There should be a spring loaded tensioner that you just have to pull up on with a wrench.