1. Open a new scene in Blender, and switch to the Scene tab. Check the Views box, and you will see a panel open up with several options. The first two options are Stereo 3D and Multi-View. Stereo 3D is easier to use for more renders, so we will select that option. This option will divide the camera into two, one for each eye, and render a separate image for each.
2. Now select your camera object, and switch to the Camera tab. Select the Panoramic sub-tab to make the camera render a full sphere. The type should be set to Equirectangular, although the fish-eye options do work better with some of the current generation of VR viewers. Confirm that the minimum and maximum Latitude are set to -90 and +90, to render everything from straight down to straight up, and that the minimum and maximum Longitude are set to -180 and +180 to render a full 360 degree view.
3. Under the Stereoscope sub-tab, check the box that says Stereo Stereoscopy. This option ensures that the two cameras effectively rotate to cover different parts of the scene. If this box is not checked, your final result will have proper depth looking forward, no depth on the sides, and the depth perception will be reversed looking backwards in the VR headset. (If you know your Interocular Distance, this value can be changed. However in general this does not make much difference to the final result, and will also vary among different viewers)
4. Ensure that the camera object is level. You may want to focus on some object in your scene that is lower or higher than the camera, but this does not work well in a virtual reality render. Use the Object tab to set either the X or Y rotation to 90 degrees, and do not change these values.
5. Construct your scene the way you normally would, making sure though to check the lighting and the scene in all directions. In VR renders you cannot simply push problem areas out of the field of view!
6. Render your scene, and you should have two images in the final result. You can check both images using the menu at the bottom of the render window, in a drop-down menu labelled "left" and "right".
7. Save the image, but set a couple of options first. In the Save window, there will be an option "Views Format:" and two drop down menus. Select Stereo3D, and then under Stereo Mode select either "Top-Bottom" or "Side-By-Side". Now you can save the image, and it will automatically be in the correct format for use in a VR headset.
8. Open the image in a program such as VR-Player, and set the image format to either "Top-Bottom" or "Side-By-Side" (depending on what you selected in Blender). If everything worked properly, you should see your rendered scene in the headset.
So that is how you create a VR render. I hope you try it out, and make some amazing and immersive scenes!