You create a custom app using the Custom List app. The Custom List app creates a very basic list app that you can then customize for your particular scenario.
Follow these steps to create a custom app:
- Click the Settings gear icon and select Add an App. The Your Apps page is displayed. 
- Click the Custom List app on the Your Apps page. - The Adding Custom List dialog box appears.  
- Provide a name for the app in the Name text box. - To make things simple, you only need to give your new app a name. However, if you want to provide a description, you can click the Advanced Options link. - The name you type here is used in the app’s web address. Avoid using spaces in the name when you create the app. You can change the app’s name to a friendlier name after you create it. 
- Click the Create button. - SharePoint creates your new app and takes you automatically to the Site Contents page. Your new app has a green New! tag next to it to let you know it is a new app. 



