The manuals with (most) head units are very easy to understand and quite thorough.. Considering the age of the car as well, it would be a very simple installation.
About the only problem would be how to get to the brackets, which is usually just a case of ripping the facia bits off in the right order, in which case I can't help you out at all..
Also, try and get a wiring harness adapter, these little beauties plug into your existing wiring harness (the plug that would've been left behind sitting where your stereo used to be) and the new one.