I believe the PDF should be on your install disc.
It would be the Getting Started Manual. I don't have GTP4, but I do have a copy of this.
The Help files are much more informative.
You should be able to access these from your toolbar in GTP4. Help>Help Topics. Or you can go directly to them from the GTP4 folder in Program Files in Windows Explorer.
There is also lots of valuable information in Support, at the top of the forum page. Click GTP4, then Tech Tips.