VRAM is basically 'Video RAM' just so this is made clear for you. Take a look at this website it should provide you with some information. If it doesn't tell you where to get the VRAM from then Google search it or try http://www.overclockers.co.ukbut look at this site for information; http://www.pcguide.com/ref/video/techVRAM-c.html
WAY back when, some video cards allowed you to upgrade your VRAM. But today, there's really no way to. Some computers with onboard video may have the ability to bump their shared memory up, but it really makes no difference.
Realize, RAM means very little on video cards. Even if you can bump it up on your card doesn't mean it'd work with the program. You need to look at video card's actual performance and benchmarks(assuming you plan on upgrading )