Copy these files to "Oblivion" folder (where you can find Oblivion.exe). If you have a Steam version of the game, it will be located Steam\steamapps\common\Oblivion. Done. You've installed it. Now you need to tweak the enblocal.ini:
First and foremost, you need to determine your VideoMemorySizeMb= value.
To do so, download VRamSizeTest:
http://enbdev.com/download_vramsizetest.htm
Inside the archive you'll find VRamSizeDX9.exe. Oblivion is a DirectX9 game, so copy VRamSizeDX9.exe to "Oblivion" folder and load the .exe.
Memorize the number you've got from the VRamSizeDX9.exe subtract the following values:
170 - if you have Windows 7,
350 - if you have Windows 10,
and subtract nothing if you have Windows 8\8.1.
The number you get is a VideoMemorySizeMb value. Example:
You use Windows 7 and VRamSizeDX9.exe gives you 7872.
7872 - 170 = 7702 (MB) and that is the value you copy in your enblocal.ini.
[MEMORY]
VideoMemorySizeMb=7702 ; change it to:
[MEMORY]
VideoMemorySizeMb=yourvalue ;
next, you need to tweak ReservedMemorySizeMb. To determine this value you need to keep in mind two things: the amount of VRAM and stuttering in your game. For example, you have 1GB of VRAM. Start with 128 value:
[MEMORY] VideoMemorySizeMb=128 ; increase that value (128, 256, 512, 1024), until the stuttering is gone or are minimal at the smallest VideoMemorySizeMb value. The biggest possible value is 1024.
Meaning: the smaller the value, the better, but there should be no stuttering. High VideoMemorySizeMb values lead to crashes.
If you want to use ENB, you'll have to use d3d9.dll from ENB archive as an additional library. Just rename your ENB d3d9.dll to other_d3d9.dll. In enblocal.ini change the following lines:
EnableProxyLibrary=true ;
InitProxyFunctions=true ;
That's it.
If you're too lazy to tweak any of these, you can use my ENBoost+ENB+FXAA Injector preset: