Reshade is fairly straightforward thesedays. From memory the process is just:
- Download and launch the Reshade setup executable.
- Browse for the main game executable. Reshade will also have a button to select depending on whether the game you want to target uses DirectX/OpenGL/Vulkan.
- It'll pop-up a list of default shaders that will download if selected (they're all selected by default but they don't take long to download).
Following that it installs into the game directory the DLL injector and a directory of settings/shaders. Then just launch the game and you should see the Reshade in-game UI notify of what hotkey to press to bring up the full Reshade UI.
From the UI a preset/profile can be created (think of them like a grouping of shader settings you configure) and then the shaders you installed earlier during the setup can be configured and enabled/disabled as you like. Also general settings can be configured in a pretty easy-to-use UI. Many years ago this all used to be done exclusively via text files (and it still can be if one prefers). You'll see changes live.
When I do use Reshade it's typically for either sharpening a game's TXAA (using the LumaSharpen shader) or disabling the game's own AA (if it's wonky) and using one of Reshade's AA shaders.