Precompiled JAR files
You can download the latest stable version, 1.26 at the downloads page, http://arianne.sourceforge.net/?arianne_url=games/game_stendhal#downloads You can also use Git, but that code is actively developed and may be unstable. If you use the Git version, you must also compile the files, and create the JAR files.
Java Webstart is a method of loading a blah.jar file, from the web. A user clicks on that link, and java handles the content, whatever it may be.
All you have to do is goto the main stendhal page at http://arianne.sourceforge.net/?arianne_url=games/game_stendhal and click on the "Play" image.
Source Code Via Git
Anonymous Git Access
To download the latest Stendhal source code with read-only access use the following command from a terminal or command line:
git clone git://git.code.sf.net/p/arianne/stendhal
This will download the entire remote source code and create a local repository. To update the local repo at any time the git fetch, git merge, or git rebase commands can be used. Each uses a different method for adding changes locally. It is advised to read up on the differences.
Privileged Git Access
Sourceforge accounts with read/write privileges to the Arianne Git repositories can use their Sourceforge username and password to gain access via SSH:
git clone ssh://email@example.com/p/arianne/stendhal or git clone https://firstname.lastname@example.org/p/arianne/stendhal
You will be prompted for your SF password afterward. To commit changes use the git commit command and git push to push changes to the remote master repository. If the local repository is out of sync with remote it will be required to do a synchronization prior.