Go to the Forge website and select the minecraft version you wish to get forge for from the list.
You can download the installer for the Recommended Build or the Latest build there. Latest builds may have newer features but may be more unstable as a result. The installer will attempt to install forge into your vanilla launcher environment, where you can then create a new profile using that version and play the game!
For support and questions, visit the Support Forum.
Here is a short video from Rorax showing how to install and setup Forge:
See the "Getting Started" section in the Forge Documentation.
If you wish to actually inspect Forge, submit PRs or otherwise work with Forge itself, you're in the right place!
See the guide to setting up a Forge workspace.
See the "Making Changes and Pull Requests" section in the Forge documentation.
We require all contributors to acknowledge the Forge Contributor License Agreement. Please ensure you have a valid email address associated with your github account to do this. If you have previously signed it, you should be OK.