I’m sure you’re asking in regard to this post: https://kinkeadtech.com/2014/12/xbox-one-xbmc-kodi-live-tv-oneguide-integration/
In that guide, I go into a bit more detail having to do with the OneGuide integration with Kodi Live TV, but it sounds like you’re asking about the very first step of getting Kodi on the Xbox One.
Well, there is no Kodi app on the Xbox One (yet). What I did was plugin my home theater PC (HTPC) “HDMI Out” into the Xbox One “HDMI In” as if my HTPC was my cable box. Then when you open the TV app, or say “Xbox Watch TV” if you have Kinect, then it will show the video output from your HTPC which would be running Kodi.
If you have any more questions, please let me know. I would be glad to help. Thanks.