^ If your talking about Daz's Fog Color Post, then this is what he is showing you what to do.
Open ModWiz (or Mission Folder), I think its Shift S or Shift M to make a screen pop up. On that screen, it should say "fog color". Enter one of the RGB Numbers in the space that opens when you click "fog color", Save Mission, then when the mission reloads, you should see the fog color you picked.
If your talking about the post Gar and I made, Then what we said takes place in the same place where you click "fog Color". To get rid of Fog, I think It is Fog Volume 1,2 and 3 that you change to 0. Each Fog Volume receives the number "0" in its blank.
For the Mission Area, The most used for Original TT mods is -512 -512 1024 1024. You open up "mission area" then, and enter -512 -512 1024 1024.
I havent used ModWiz for a lllloooonnnngggg time, So Im not sure about the Buttons and key bindings and all that stuff.
Hope it clears stuff up for you.
Stay Squishin,
-Squishin