Brian;
Well, if you want to create a CIN (or a DLL, which is usually preferred), then to learn C is an issue you need to address now.
You need to read the official manual
Using External Code in LabVIEW, which is also included with your copy of LabVIEW. For CIN, you can refer to the following article:
How to build a CIN code resource (.lsb file).
I am not an expert in C but, looking at the code, it seems that you can do that completely in LabVIEW, without the need to write or handle any C code. The code is small, consist of only three actions and you can do a better error handling. I'll see what I can find out later on...
Regards;
Enrique
www.vartortech.com