Creating tags from the command line:

To create a tag on your current branch, run this:

git tag <tagname>

If you want to include a description with your tag, add -a to create an annotated tag:

git tag <tagname> -a

This will create a local tag with the current state of the branch you are on. When pushing to your remote repo, tags are NOT included by default. You will need to explicitly say that you want to push your tags to your remote repo:

git push origin --tags

From the official Linux Kernel Git documentation for git push:

--tags

All refs under refs/tags are pushed, in addition to refspecs explicitly listed on the command line.

Or if you just want to push a single tag:

git push origin <tag>

See also my answer to How to push a tag to a remote repository using Git? for more details about that syntax above.