Don't need worry about a fire, unless you work on the car when it is smoking hot. I'd wait until everything cools completely down - otherwise, you'd make this a much harder project than it needs to be.
In this pic:
Right underneath the number 6 - is the "bolt" that you will need to put a wrench on to loosen the tension on the the serpentine belt tensioner. Slip a wrench over that fake nut - pull toward the front of the car and that will compress the shock like strut, to the left, and loosen the belt. Once tension is off the belt, you can slip it off the pulleys. Make sure you note how that belt runs over the pulleys to make sure you can slip it back on the right way.
Helps if you have a second person there - one to slip the belt on, while another helps hold the belt on certain pulleys and help work the tensioner. Otherwise, you'll have to be creative in how you hold the belt so it doesn't slip off the pulleys.
There are several DIY with decent pics listed in the forum - should be able to search for those to get a better idea of what to do here.
^
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