If you go into the main media screen and press the menu key you can select "Explore" which will let you browse directories on your Blackberry like on Windows. You should be able to select the file and view it from there.
I dont think you can view native docs even in folders from your sd card. You cant edit them (without added sortware) or attach them to an email either as far as I can tell. You can send them via bluetooth (whatever use that is)Its very limited really. Follow penguin3107's advice and at least you can view them and forward them to others.
If you go into the main media screen and press the menu key you can select "Explore" which will let you browse directories on your Blackberry like on Windows. You should be able to select the file and view it from there.