The question "is how to install the RA2:YR mods".
It usually works that the mod files are added to the folder with the main game files:
Spoiler (click here to read it):
Ares.dll
Ares.dll.inj
ares.mix
BINKW32.DLL
Blowfish.dll
expandmd01.mix
gamemd.exe
langmd.mix
language.mix
movmd03.mix
Phobos.dll
Phobos.pdb
ra2.mix
ra2md.mix
RunAres.bat
Syringe.exe
thememd.mix
But in mods with CnCClient support *it seems like* a launcher for mods is meant?