To get started with Android, you'll need to get familiar with Source Control Tools.
To initialize your local repository using the LemonageOS trees, use a command like this:
repo init -u https://github.com/LemonageOS/android_manifest.git -b lineage-18.1 --git-lfs
Then to sync up:
repo sync -c -j$(nproc --all) --force-sync --no-clone-bundle --no-tags --optimized-fetch --prune
Initialize the ROM environment with the envsetup.sh script
. build/envsetup.sh
Lunch your device after cloning all device sources if needed
lunch lineage_codename-buildtype
Start compilation
mka bacon