My uncle has the same version but he's running it on windows xp and he runs the 32 bit version, and when he starts Sonar, in the 'MIDI Output' prompt in the beginning, he has the Virtual Sound Canvas appearing. What should I do so it works?

What should I do so it works?

 
The smart-aleck answer would be... get another computer running 32-bit XP.
Roland has some info on the VSC here http://www.roland.com/products/en/VSC-MP1/
but none of it is good for you...
except the part where it says the VSC has both DX and VST versions included.
You may be able to use it if you install and run the 32-bit SONAR PE and set the OS up to run SONAR in 32-bit compatibility mode.
 
As far as your uncle having the VSC listed as his MIDI device, I don't know how that's done unless at some point he had the hardware VSC.

Okay, I installed Sonar 6 PE under 'Windows xp SP3' compatibility mode. VSC didn't want to install, so PGMusic said that ForteDXi could be used instead. Though, I still don't see ForteDXi in any field, that being either Instruments or MIDI Output