hmm .. let me try help you...
1)Double click on those Foxyproxy icon on the you bottom right Firefox window. This will open up FoxyProxy option.
2)You should be on "proxy tab" and then choose the BolehVPN, click "Edit Selection" The "FoxyProxy - Proxy Setting" window will open up.
3)Click Add New Pattern. "FoxyProxy - Add/Edit Pattern" window will open.
4)Fill the Pattern name, tick the Enable box on top.
5)In the URL pattern you should add something like *.whatever.com/*. Click Okay and all done.
6)You can recheck at the "FoxyProxy - Proxy Settings" The new pattern should appear there and the small tick appear on the enable column.
hope that help