Depends on the patch. Some have batch files for execution some don't.
Simple way to install such things for MGE is this:
Right click on the civ-2 shortcut icon.
Select properties.
Select find target.
Place the patch directly into the pop-up box you see after the find target selection (you should see all the programs for the game here).
If it asks to replace an existing file of the same name, you can simply click yes (the old file is hard-coded to the cd, if you reinstall civ-2 gold, the lost program is there). Or, you can just remove the old file, by placing it in a folder outside of civ-2, then place the new file in this area.
That's all there is to it.
