Please use CMSSW_8_0_24_patch1.
Download and execute the setup script:
wget -O /tmp/checkout_80X.csh https://raw.githubusercontent.com/CJLST/ZZAnalysis/miniAOD_80X/checkout_80X.csh
cd $CMSSW_BASE/src
cmsenv
source /tmp/checkout_80X.csh
In the package directory, simply issue
git pull
To commit directly (you need write access to the repository):
git pull
[edit files]
Once you are ready to commit
git pull
git add [files to be added]
git commit -m ["commit message"] [files to be added]
git push origin miniAOD_80X
Otherwise you can make a fork of the repository, develop therein, and make a pull request in the same way as for CMSSW.
Please see the gitHub wiki for more documentation.