Heater Core R&R

I have a 95 GMC Jimmy SLS 4.3L with A/C. Seeing a puddle of antifreeze on the passenger floor told me the heater core has blown. I dont have any idea as to how to access the heater core....can anybody get me started?

Thanks, and thank you all for being here to help.

With all of the steps involved it would be better to get a manual (Haynes).

Or try autozone.com, repair guides, some steps may be oversimplified, but you will get the idea, this is a tough job!