How to: Add Items to a SharePoint Project
SharePoint solutions contain one or more projects, each one containing multiple SharePoint project items. After opening or creating a SharePoint solution, you can add either new or existing items to these projects. For example, new workflow projects come with a default form named default.aspx, but you can replace that form with a new or different form, or add another ASPX form.
To add a new project item to a SharePoint solution
Open a SharePoint solution in Visual Studio or create one.
Click the project's node in Solution Explorer.
On the Project menu, click Add New Item to display the Add New Item dialog box.
In the Installed Templates list, expand the SharePoint node, and then click 2010 .
Select a project item template in the list of templates.
Enter a name in the Name text box and click OK.
To add an existing project item to a SharePoint solution
Open a SharePoint solution in Visual Studio or create one.
Click the project's node in Solution Explorer.
On the Project menu, click Add Existing Item to display the Add Existing Item dialog box.
In the Add Existing Item dialog box, browse to the folder that contains the item that you want to add.
Select the item and then click Add.