Stay away from GitLab if you run CentOS (>= 6) !!
No matter what way of install you select, you will end up with broken gitlab and/or broken whole system. I personally do not recommend GitLab as a git server in production environment.
If you really want to go with GitLab, try to install it in test env first, or go here and let GitLab host your repo for you (you can either import repo, upload files, or create new one). Just remember to set visibility to private.