Hi Sanjay,
If you want your readers to be able to see the coordinates of point features on a web map when they click on them, you could configure popups for the layer in your web map containing those features. If the coordinate values are attributes in the table for that layer, you can include those attributes in the popup that your readers will see. You do that popup configuration in the ArcGIS Map Viewer. To add point coordinates into the layer's attribute table as field values (if your data doesn't already have these fields) in ArcGIS for Desktop you could use the Calculate Geometry command or Add XY Coordinates tool, or in ArcGIS Online you could use the Extract Data analysis command.
If you want your readers to be able to see a coordinate readout showing them the current location of their cursor as they move it over the map, that is something that the Story Map apps don't have a built-in option for. In the ArcGIS Map Viewer people use the Measure control to see this readout, which opens a dialog in which the info is displayed. The Story Map apps don't have the option to expose the Measure control when they display a web map. However there are other configurable apps in ArcGIS that do give you the option of adding a Measure button into the app, like the Basic Viewer. For example you could create a Basic Viewer app from your web map, and turn off unwanted controls but turn on the Measure control. Then you could embed that Basic Viewer app into a section of your Story Map Journal (using the web page option) so that your readers can use the Measure control. The UI won't look quite the same as other web maps in your Journal, but it is a useful way to get additional functionality into your story map.
Rupert
