Right click the installation folder for Zero Hour (the folder you've already been working with all this time), click Properties.Under Compatibility of the new shortcut, uncheck the box for Compatibility mode and Run this program as administrator, this is necessary to run ReShade, however, it causes issues where gamefiles can't be overwritten or changed because permissions are denied.Duplicate your existing ZH shortcut, naming it something like ZH-ReShade, right click it, go to properties, then add the following to the commandline: -proxy d3d8to9.dll (the same way you enable windowed mode or quickstart).In the final step of the setup, click Edit ReShade Settings, select the Preset by ExiLe.ini and press OK to finish the installation.Run the Reshade Setup, in the first step select generals.exe in the ZH installation directory, make sure to install the Direct3D 9 version.Copy the d3d8to9.dll and the Preset by ExiLe.ini file into your ZH installation directory (that is C:\Program Files (x86)\EA Games\Command & Conquer™ Generals Zero Hour).Our ReShade expert ExiLe's Preset: Preset by ExiLe.ini
The latest version of ReShade from the official site: Step One: Downloading The Necessary Files Whatever your interest, and if you're interested or not, here is how you use it.