Juan,
Do you have to use an FLL? In VFP it's much easier to use DLLs, There is an example of how to do this on my website in the spyin.zip file using VFP5 and VC++5.
There is some documentation on FLLs in the online documentation and there are a couple of MSKB articles available.
>Can I know where to get documentations related to writing a FLL (FoxPro Library)?