You need to make sure you have SteamVR installed , as well as Windows Mixed Reality for SteamVR (Just go into steam and search windows mixed, you'll see it.) Make sure you have everything setup and windows mixed reality is functioning properly. (Go through the initial setup of both Windows Mixed Reality and then SteamVR.)
Once it's all setup, there are multiple ways to start it. First with every step, you need to start windows mixed reality. (It should be called Mixed Reality Portal in your start menu.) From there you can either:
1. Start SteamVR from inside of windows mixed reality. (I usually just hit the windows button, get to the menu, and open up desktop. This way I can navigate with the motion controllers from inside of windows mixed reality and start SteamVR or elite dangerous from steam.)
2. With Windows Mixed Reality running, take off your headset, and use the mouse and keyboard to start up elite from Steam. (When you hit play, it'll ask which version you want. Elite Dangerous, Horizons, or Elite Danerous VR. Obviously pick elite dangerous VR)
I would suggest after starting windows mixed reality, running Dr. Kaii's awesome tool, EDProfiler. It'll allow you to easily set your settings for VR (Or the desktop version for that matter) before you start elite. (You must start elite on the computer the first time though or it won't work. I think the initial config files need to be written, but don't quote me on that part.) Pick your settings, hit apply, then start elite. Of course this isn't required, just useful.
