is the site working at all? (EDIT: just checked looks like it's not).
Don't worry about there not being a dev folder, there isn't one, all actions in SS are directed to main.php via the htaccess file. I notice that your SS install isn't in the root of your site, so make sure that line 10 of your .htaccess file reads:
http://timdonaldson.com/silverstripe/ is working for me, although pretty slow because it's hosted on Mediatemple without being cached — I'm just using as my test server until I get my head around things.
Cheers for explaining the lack on dev folder. Am I adding that line to my root .htaccess folder or the silverstripe folder? What does Rewrite do?