As Joe stated, WinRunner is designed to run on the Windows operating system. (You probably should have been aware of this when you acquired the software.)
That having been said, if you have no other options (read: no Windows boxes on which to install WinRunner), you can try to install WINE - http://www.winehq.com/ - on your Linux box and then load up and run WinRunner. I wouldn't advocate this as you don't know what you're in for (read: more headaches than it's worth?)...but you can always try.
Before going down this road, I would want to make myself fairly fluent with what WINE can and cannot do.
Another thing to keep in mind is that if you do go this route, you may get much in the way of support from Mercury.