I tried spraying some belt degreaser and it seemed to help until I got down the road, anyway it's a 2001 mazda b3000 dual sport 2wd and I cannot figure out how to tighten the alternator fan belt on it, the alternator does not rotate up or down so I cannot tighten the belt, if you know please let me know if you can.

Read the link below on serpentine belts:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-5.html#post578394

You likely need to replace the old belt, if it's worn or squealing. Easy job.