I am trying to figure out how to replace the Fuel Pressure Regulator on a 1999 Blazer V6. Someone that knows, or has a link to it, please help. Pictures would be a plus!

If your wanting to replace the injector assembly, I recommend upgrading to the MFI. It's cheaper and more reliable. The parts can be purchased from www.GMPartsDirect.com for less than $200. Here's a TSB that covers the installation (Page 9, I think).
http://www.myfilehut.com/userfiles/13931/059041%20CLEAN%20CSFI%20POPPIT%20VALVES%20OR%20CON VERT%20TO%20MFI.pdf
All the part numbers are at the bottom. The FPR is part of the new assembly and included in the price.

Any reason that you're wanting to replace yours? Other than clogged poppit valves, they rarely go bad on the 96+ engines.

I took it in to a shop and they told me that the Fuel Pressure Regulaor was bad. I figured I could do it my self.

How do you clean the poppit valves?

Techron fuel injector cleaner works well. A 20 ounce bottle costs about $10. Just add it to your gas tank and fill up. It may not be necessary for you to use it though. Let's start at the beginning, what kind of problems are you having? Did the shop say that the FPR was bad beause it's leaking or because of fuel pressure issues? If because of fuel pressure issues, did they check the pressure at the filter to verify that it was indeed the FPR and not the pump?

How would I check the fuel pressure?