How to disassemble Citra Xantia 1.9SD Alternator

Good, I'm new here and the truth is that I don't know if they can give me a hand? I will explain, I have to change the air compressor and it is broken but I don't know how the alternator's strap is weeding. I have loosen a tensioner that carries a crescent but I am very wearing even more, how can I approach it? Thanks in advance if you can help me, greetings