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The first thing you need for your truck b4 you do anything else is buy a shop manual for it. The Haynes or Chilton's manuals will probably serve you well.
The process is too long for me to try to provide here. Use the manual or someone else may want to type it all in. The manual has diagrams in it.
I agree with Pats, go buy the Haynes manual. Not only will it tell ya exactly how to replace it, but it'll give ya the extra information on what is going on that you will hopefully appreciae, as well as pretty pictures. If you decide not to go that route, just loosen the idle tensioner pulley bolt till it pops back (relieves tension) and then remove alternator bolts, remove alternator and/or regulator plugs from sockets on alternator, remove alternator, and then reverse for installation.