This is an unofficial installer for GmodDotNet (https://github.com/GmodNET/GmodDotNet).
- Download right zip from https://github.com/DasDarki/GmodDotNet.Installer/releases/tag/1.0.0
- Unarchive the zip
- Run the GmodDotNet.Installer file
- Go through the installation wizard
- Have fun :)