Game settings?
Both your posts refer to terms that are unfamiliar.
You need to let us know exactley what you want to do. What sort of Mod do you want to make and are there going to be any new items in your Mod.
If you are thinking of building a Mod based on the Half-Life engine that uses all the available resources, then you don't need to code or change the FGD.
If you want to create a game from scratch that doesn't use the available resources... then you will need an understanding of C++ and how to work with the HLSDK.
The latter topic is way above the 'scope' of this site.