To get started with manifest/BeastROMs, you'll need to get familiar with Repo and Version Control with Git.
To initialize your local repository, use a command like this:
repo init -u https://github.com/BeastRoms/platform_manifest.git -b 10
Then to sync up:
repo sync --force-sync --optimized-fetch --no-tags --no-clone-bundle --prune -j8
From root directory of project, perform following commands in terminal
$ . build/envsetup.sh
$ lunch beast_$device-userdebug
$ mka bacon beast