a nice idea for mod

[satlazone]

unfortuneally my programming skills are a little bit low, I have a modification idea and its something I want to install into my board.
what is does, is a replacement variable for specific links (mostly download links) for specific groups (guests.)
the code will go something like this:
if usergroup=1
text=abc.com/go/123/
replace=abc.com/go/*/

just replace the numbers with * for the guest usergroup
as I said, my programming skills are low but I still know some.. how and where do I start to turn this idea into mod?
thanks for helpers!.