Most SharePoint 2013 apps are based on lists. Creating your very own SharePoint app may sound a little daunting, but creating and customizing an app couldn’t be easier. The easiest way to create your own app is to start with a Custom List app and then customize it for your particular need.
Click the Settings gear icon.
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Select Add an App.
Click the Tasks app.
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You can find the Tasks app in the list of templates.
Enter a name for the Tasks app in the Name text box and then click Create.
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In this case, the app is called My Tasks.
The new My Tasks app appears in the Recent section of the current navigation.
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It also appears in the Site Contents page.
Click the app to open it.
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Then click the New Task button to begin creating tasks.