Hi justin,
Your LCD is an Optrex 8 char x 2 line display.
It, like almost all character LCD's uses the de-facto standard Hitachi LSI HD44780 or equivalent.
I have many paper manuals for these so have never looked on the web, but I am sure if you search for the above part number you will find what you need.
The problem is that before you see anything you have to initialise the display with a few setup bytes (or nibbles in your case, this is part of the setup)
There is also some relatively slow timing involved.
You usually make a few functions to write setup bytes and data bytes that include the timing. Then they become fairly easy to use. If you find some code it may be for a direct connection where MCU i/o is connected directly to the display, but using a '595 is also a fairly popular arangement.
Hope this helps
Regards David