Hi Bruce,
Well, the first thing I'd do is download Microchip's MP Lab software. It is free here:
**broken link removed**
You will also find Tons of documents, data sheets, application notes, etc. there.
The HiTech compiler will run inside of this environment, and the environment has a simulator/debugger built in. It all integrates very nicely. You can get the free version here:
https://www.htsoft.com/products/PICClite.php
but the free version doesn't support the 16F76, however it will produce a hex for the 16F627A part, which is roughly the same, but doesn't have the AD converters. If you need AD, you could use the 16F877A.
You should be able to find a manual, and tool to install the compiler into MP Lab as well as other support docs on their site.
There are other C compilers which are free, or at least have a demo mode: CC5X, which is well liked by many, can be found here:
https://www.bknd.com/cc5x/
It supports the chip you want to use, as well as many others. Worth looking into! The commercial version is low priced, too, where HiTech is about a thousand dollars, CC5X is 250.
Also sourceboost is well liked by some. It can be found here:
**broken link removed** however the page wasn't loading when I tried. Sever down temporarily?
BTW, HiTech also produces a C compiler for the '51, too bad your original source wasn't built with this, it would be a snap.
Hope this helps you get going.
Regards,
Robert