Once you have it added to your library, go back to your console and from the menu screen, select Mods. Once you are there, you can select what mods you want to apply to your Skyrim on that console by clicking on the desired mod and then clicking on add to library.
Once you are logged in, you should be able to see the mods section in the menu (or click on this link which has the xbox one filter applied). You first need to have a Bethesda account, head here to login or create one.
