WinRunner is a bit older now and Mercury is pushing companies towards using QTP instead. If you register with Mercury's support site however, providing your customer number (the company will have this), you'll get access to the Knowledge Base, and be able to download documentation like user manuals etc for WR.
Cheers,
Dave
"Yes, I'll stop finding bugs in the software - as soon as you stop writing bugs into the software." <-- Me
For all your testing needs: Forum1393