Добавление тега:

git tag -a -m "Первая версия проекта" v.0.0

Добавление тега к предыдущему коммиту:

git tag -m "Первая версия проекта" v.0.0 bfd9e47

Добавление тега в репозиторий:

git push --tags

Просмотре тега:

git show v.0.0
git describe --tags

Просмотр всех тегов проекта:

git tag -l

Полный текст ошибки:

user@host:~/Progect/www$ git push
Counting objects: 13, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (7/7), 636 bytes, done.
Total 7 (delta 5), reused 0 (delta 0)
Unpacking objects: 100% (7/7), done.
remote: error: refusing to update checked out branch: refs/heads/master
remote: error: By default, updating the current branch in a non-bare repository
remote: error: is denied, because it will make the index and work tree inconsistent
remote: error: with what you pushed, and will require 'git reset --hard' to match
remote: error: the work tree to HEAD.
remote: error: 
remote: error: You can set 'receive.denyCurrentBranch' configuration variable to
remote: error: 'ignore' or 'warn' in the remote repository to allow pushing into
remote: error: its current branch; however, this is not recommended unless you
remote: error: arranged to update its work tree to match what you pushed in some
remote: error: other way.
remote: error: 
remote: error: To squelch this message and still keep the default behaviour, set
remote: error: 'receive.denyCurrentBranch' configuration variable to 'refuse'.
To /Progect/www
 ! [remote rejected] master -> master (branch is currently checked out)
error: failed to push some refs to '/Progects/git'

Чтобы исправить ошибку войдите с папку с origin репозиторием и введите команду:

git config --bool core.bare true

После этого в origin можно удалить все файлы, кроме папки .git.