Download and install Unity 3D from the link below to get started.
Once Unity is done installing, open it up and click create project.
Inside the editor look for a tab called Asset Store(shown below). Once there type SteamVR Plugin into the search bar.
Click on the first result and then hit download. Unity will open up a popup, leave the settings alone and click import. Another popup will display asking you about recommended settings. Click on Accept All.
Find the project tab and navigate to Assets>SteamVR>Prefabs. Drag the CameraRig prefab into the hierarchy view(top left tab) to add it to your scene.
Right click on Main Camera and delete it.
If you see an error such as Connection to VR server failed?
You should now be able to walk around your empty scene once you hit Play