How to organise thumbnails on home screen?

I'm wondering if someone has worked this one out yet. I just got a Samsung CB (for the record, without 3G) and it all seems pretty good. One thing I'm trying to work out is how to re-position the thumbnails of recently visited sites, like you can do on a desktop that's using Chrome.That is, 6 thumbnails are shown but I can't seem to (for example) click and drag the top-right thumb nail to the bottom left position.

Anyone know how to do this?

Clive