fill in intro-to-git page

diff --git a/doc/user/intro-git.md b/doc/user/intro-git.md
index e6ecd889495f47fa98ad944572d8c334d5a5d330..c1205a23dad65a1ea38eafa99ef3d605487eecab 100644 (file)
--- a/doc/user/intro-git.md
+++ b/doc/user/intro-git.md
@@ -5,20 +5,63 @@ title: "Intro: git"
 navorder: 4
 ---
 
-{% include alert-stub.html %}
-
-# Using git
+# Intro: git
 
 Git is a revision control system. There are lots of resources for
-learning about git. Here we just cover the specifics of using git in
-the Arvados environment.
+learning about git (try [Try Git](http://try.git.io) or [Top 10 Git
+Tutorials for
+Beginners](http://sixrevisions.com/resources/git-tutorials-beginners/)). Here
+we just cover the specifics of using git in the Arvados environment.
+
+### Find your repository
+
+Go to Workbench → Access → Repositories.
+
+[https://workbench.{{ site.arvados_api_host }}/repositories](https://workbench.{{ site.arvados_api_host }}/repositories)
+
+The "push_url" column will contain a string like `git@git.{{ site.arvados_api_host }}:example.git`.
+
+This url can be used to pull and push commits between your Arvados
+hosted repository and your VM/workstation.
+
+### Make sure your SSH credentials are available
+
+Git requires you to authenticate with your SSH private key. The best
+way to make this happen from a VM is to use SSH agent forwarding.
+
+When you log in to your VM, use the `-A` flag in your `ssh` command,
+like this:
+
+    ssh -A shell.q
+
+At the shell prompt in the VM, type `ssh-add -l` to display a list of
+keys that can be used. You should see something like this:
+
+    2048 a7:f0:fb:ad:ba:66:fd:c2:8e:58:49:3b:6b:2a:1f:c3 example@host (RSA)
+
+### Clone your repository
+
+This step copies your Arvados-hosted repository to a new directory on
+your VM.
+
+Log in to your VM (using `ssh -A`!) and type:
+
+    git clone git@git.{{ site.arvados_api_host }}:EXAMPLE.git
+
+(Replace "EXAMPLE" with your own repository's name, or just copy the
+usage example shown on the Repositories page.)
+
+### Commit to your repository
+
+This part works just like any other git tree.
 
-### Cloning the repository
+    # (edit foo.txt)
+    git add foo.txt
+    git commit -m "Added section explaining what foo isn't"
 
-### Creating your own branch
+### Push your commits to Arvados
 
-### Creating your own repository
+From within your source tree, type:
 
-### Adding MapReduce functions
+    git push
 
-### Pushing your commits to Arvados