So... this is it.
Looks easy enough for a new one.
Now off I go to import an existing sand castle :-)
-----
Hmmmmm. Tried to pull and got this:
From ...my_sandbox
   314baab..2fcb0a1  master     -> origin/master
You asked me to pull without telling me which branch you
want to merge with, and 'branch.master.merge' in
your configuration file does not tell me either.  Please
name which branch you want to merge on the command line and
try again (e.g. 'git pull <repository> <refspec>').
See git-pull(1) for details on the refspec.

If you often merge with the same branch, you may want to
configure the following variables in your configuration
file:

    branch.master.remote = <nickname>
    branch.master.merge = <remote-ref>
    remote.<nickname>.url = <url>
    remote.<nickname>.fetch = <refspec>

Soooooo..... I probably should return to that HOWTO...

....searching....
finall, http://snippets.dzone.com/posts/show/5714 has the answer:
git config branch.master.remote origin
git config branch.master.merge refs/heads/master
and I'm almost happy now :-)