I hope my question isn't that stupid
I'm using sabuzb version 0.4.12 under OS X Snow Leopard and Safari with the great looking Plush skin.
Everything works good.
But until yet I haven'f found out how I can add a local saved nzb file to the queue.
When I switch the skin to smpl I can add a nzb.......
In the 0.4.x versions of Plush there is nzb adding facilities at the top of the page in plush. These options can be hidden, which is probably what has happened in your case.
There is a hidden link you can click and single click at the top of the page in plush. Hover your mouse over in the middle at the top of the page and the link should appear. Clicking or double clicking should bring up various options, one of them being local nzb uploading.