Things You'll Need
Instructions
Unzip the mod package. Packages come in a variety compressed formats, including .ZIP and .RAR. If you don't have a compatible unzipping program, download and install 7-Zip, jZip or WinRar. They can handle the full spectrum of compression formats.
Open "My Computer" and navigate to your Oblivion directory. By default, it's located in \Program Files\Bethesda Software\Oblivion.
Drag and drop the contents of the mod into the "Oblivion" directory or one of its sub-directories. The specific location varies from mod to mod, so check the mod's readme file to find out exactly where to put the contents. Typically, .NIF files go in the \Oblivion\Data\meshes directory.
Start "Oblivion." Click on "Data Files." Check the box next to the mod you just installed. This activates it in the game.