first check the mod's forum to see which version of sins  they are compatible with  ie 1.05, 1.10-1.13 or entrenchment

make sure that you have that version of sins ie bottom righthand corner of sins menu screen

to find the location to extract the mods first turn off then hidden files & folders and hidden extensions in explorer / tools / folder options

in sins click on options, then mods then show mod path, then write down the path

on xp it typicaly is c:\documents and settings\"user name"\local settings\application data\ironclad games\sins of a solar empire\mods

on vista and w7 it is c:\users\:user name"\local settings\application data\ironclad games\sins of a solar empire\mods

then you extract the rar\zip\7z to the mods folder

in sins go to options mods click on the mod you want to use then click on the enable mod button, sins will process for a miniute or so then click on the load mod on startup

play sins with the mod

harpo