This page provides some details on how to get V-Ray up and running.
The V-Ray installer for Maya is pretty straightforward and easy to follow and can be downloaded from the V-Ray | Maya Downloads section of the Chaos Group website (please make sure you use your login credentials to ensure access to the download links). It's recommended that before installing V-Ray, to make sure your computer meets the System Requirements for running Maya with V-Ray. If you would like a step-by-step guide, please check out the Installation of V-Ray for Maya page. If you run into any problems like installing V-Ray, please check out the Troubleshooting page.