QUOTE(lil_nemesis)
Ok l am sort of new to modding in would like to learn. First of all what can you do with a mod in starcraft and second how do you make a mod?
there are many things you can do with modding, from changing a units health to creating a completely new unit (by replacing a old one)
The ways you can make a mod can vary, the most common way (that I've seen) is to use Arsenal III, IceCC, WinMPQ, RetroGRP, and MPQDraft
But since your new with modding you should probably start with just the basic editors of Arsenal III, WinMPQ, and MPQDraft
first of all, you load up winmpq and open patch_rt.mpq (in starcrafts folder) and extract arr\units.dat to the folder you want to create the mod in (if the MPQ has alot of unknowns then you will need to get a listfile for loading them)
second of all, open Arsenal III's unit editor and open the units.dat file you extracted then start changing the units stats and weapons and stuff to play around with Arsenal III so you know how to use it later on
third of all, after you've finished with your units.dat file (and saved it) load up WinMPQ and create a new MPQ then, import your modified units.dat file and when it asks for a folder tell it arr\ (the \ is importaint so dont skip it or put / instead)
finally, load MPQDraft and tell it to load MPQ_PATCH, on step 1 where it asks for program executable browse for starcraft.exe (in starcrafts folder) and click next, on step 2 browse for your newly created MPQ and then click next, on step 3 just click next
and after all that you've finally made a mod and starcraft will open letting you test it