Add Button to sharepoint Ribbon control using visual studio 2012

In this task, you will add a custom action to the ribbon of all Document Libraries to launch the App.

1. In Visual Studio, right click the HelloApp node and select AddØNew Item from the Context menu.
2. In the New Item dialog, select Ribbon Custom Action.
3. Name the item Launcher and click Add.

Create Client Web Part to the App using visual studio 2012

In this task, you will add a Client Web Part and code it. This web part can be used on pages outside of the App to add functionality to the hosting SharePoint site.

• Add a Client Web Part
• In the Solution Explorer, right click the HelloApp project node and select Add-->New Item from the context menu.
• In the Add New Item dialog, select Client Web Part.
• Name the new item MyClientWebPart and click Add.