Hi Anthony,
Your dll file should contain a list of functions. When you use the Call Library Function (CLF), right click it and select configure. Select the right dll and function name in the dialog box. More information on using CLF is found in this document under 'Shared Library'
http://www.ni.com/pdf/manuals/370109a.pdf
You will also need to refer to the card manual for initialization routines/functions and starting the input/output processes.
I have also been through a similar process where I had to interface a non-NI instrument with labview. I found that a well written instrument manual really helps.
Hope this helps. Good luck.
-Setu