Dissconnets

I need to update the firmware on my Motorola br700 router.
I can access and log into the router OK via my browser but when I try to update the firmware it just seems to freeze and/or seem like it's taking far too long.
It has a "browse" option also next to the "update" option, so I'm guessing I have to download or have the firmware update file there in order to update it, only problem is, I can't seem to find it anywhere. Any help would be greatly appreciated, cheers.

Watty