Things You'll Need
Instructions
Download a texture pack. Tweak Guides covers several of the major texture replacements, while the most complete collection is available at The Elder Scrolls Nexus.
Unzip the texture pack. Windows 7 comes with native unzipping software, while versions of the operating system require you to install a third-party program, such as 7-Zip or WinRar. 7-Zip is free and open source, and WinRar has a free 30-day trial.
Open "My Computer" and navigate to your "Oblivion" textures directory. By default, it installs to "C:/Program Files/Bethesda Software/Oblivion/Data/Textures."
Drag and drop the texture files into the textures directory. Texture files have the extension ".dds." Some are located within a subdirectory, such as "Textures/LandscapLOD/Generated." If that's the case, drag and drop the entire folder into your textures directory. That way, texture files will end up in the proper subdirectory.