You can create an app by putting a shared map into a template and configuring it to create a customized look and feel. Different templates offer various bits of functionality, such as different layouts and color schemes, editing and identify tools, social media feeds, side-by-side map viewers, and so on. Once you have found a template you like, either from the map viewer or the Gallery, publish it on ArcGIS Online and configure the components. You need privileges to create content in order to publish your app to ArcGIS Online. As an alternative, you can download a template and deploy it to your organization's web server.
Create an app starting from the map viewer
If you have privileges to create and share content, you can use the map viewer Share to find the template that best suits the story you want to tell with your map. As an alternative, you can find templates in the Gallery or by searching ArcGIS Online.
Verify that you are signed in with privileges to create and share content.
Open a saved map in the map viewer and click Share. You can only make an app with a map that is shared. If you own the map, share it by specifying sharing options in the Share window. If you don't own the map, contact the owner and have them share it as necessary.
Click Make a Web Application. The Make a Web App window opens with a gallery of templates you can use to create your app.
Hover over a template thumbnail to see a description of the template.
Click Publish under the template thumbnail and choose Preview to see how your map will look in the template.
Click Publish under the template thumbnail and choose Publish to start creating your app.
Type a title, tags, and summary for your app and check the box to share the app with the same people as the map (for example, if your map is shared with your organization, your app will also be shared with your organization).
Click Save & Publish.
Your app is published to ArcGIS Online and an item is added to My Content. The configuration page automatically opens.
Set the configurable components of the app such as the color and title, menu items, and widgets. Click Save when you are done.
Create an app starting from the Gallery
As an alternative to using the map viewer, you can discover app templates from the Esri-featured section of the Gallery.
Verify that you are signed in with privileges to create content.
From the Gallery, open the Esri Featured Content section and click Apps.
Click Configurable Apps to see the Esri templates you can use to create your app.
Hover over the template you want to use and click Details.
From the details page of the template, click the thumbnail (or Open and View Application) to open a preview of the template with a sample map.
Click Publish Application to start creating your app.
Type a title, tags, and summary for your app and click OK. Your app is published to ArcGIS Online and an unshared item is added to My Content. To make your app accessible to others, you need to share it.
Select a map to use and change any other configurable components in the app such as the theme, widgets, and miscellaneous items. Click Save when you are done configuring the app.