ArcGIS for Windows Phone is a map viewing app: it does not contain an authoring experience. However, you can author your maps to use your geographic information system (GIS) data within the app. To author maps for use on the phone, create a map and host it in an online GIS or mobile content server. The workflow for creating a map depends on where the map will be hosted.
If your map will be hosted through an online GIS such as ArcGIS Online or Portal for ArcGIS, you can use the browser to author your map with the map viewer. See Make your first map in the ArcGIS Online Help system for details.
If your map will be hosted on your ArcGIS Server using mobile content server, the map will be manually authored. See Publish a map to your ArcGIS Server.