Two series of slides: Introduction to Git and Using Git. The first is new, the second is more detailed. Then follow by Collaborative Development and Open Source Projects.

You can also buy the book: Collaborative Development using Git and GitHub.

Collab dev series

The Git series

Git on MS Windows

Git on Windows series

Other articles

Getting Help for Git

Besides just typing your question in your favorite search engine, there are several places right on your command-line that can provide you help with the commands of git. 

$ git help             # listing the most important commands
$ git help COMMAND     # man page or local web page
$ git COMMAND --help   # the same

$ git help help        # help about the help system
$ git help --all       # list all the git commands
$ git help tutorial    # a simple git tutorial

Creating a local Git repository

The power of Git comes from two main sources. Its local capabilities and its networking capabilities.

The local capabilities give you a superb version control tool. The networking capabilities allow you to collaborate with others at ease.

Let's take a look at the local capabilities.

As mentioned earlier we are going to use the command line.

Open your terminal. Navigate to a directory where you keep your projects.

For example use a directory called "projects" and inside that directory create a subdirectory for each one of your projects.

On Linux or OSX: 

cd
mkdir projects
cd projects
mkdir try-git
cd try-git

On Windows it is almost the same, except that we put the "projects" directory in the root of the c: 

cd /c/
mkdir projects
cd projects
mkdir try-git
cd try-git

Initialize git in the current directory

Type in the following command: 

git init

The response will be something like this with the full path of the directory on your system. 

Initialized empty Git repository in /Users/gabor/projects/try-git/.git/

This command created a directory called .git (with a leading dot) that contains the "database" of Git. In general you should not change anything in that directory manually.

Using the ls command with the appropriate flags we can see that this is the only item in our directory. 

$  ls -Al
total 0
drwxr-xr-x  9 gabor  staff  288 Apr  6 18:19 .git

How to get the most recent tag in a tag series?

Let's say a build process tags each commit that was used by a build and puts the build number on that tag. e.g. use tags like build-42

How do we get the most recent one?

Update the local git repository: 

git checkout master
git pull

List the 5 most recent build- tags: 

git tag -l 'build-*' | tail -5

The same with full sha: 

git tag -l 'build-*' --format '%(refname:strip=2) %(objectname)' | tail -5

The same with short sha: 

git tag -l 'build-*' --format '%(refname:strip=2) %(objectname:short)' | tail -f

git commits on one branch but not on another branch

git log one --not another