How to: Add and Remove References in Visual Studio (C#, J#)
The Add Reference dialog box can be used either to add or to delete project references. This dialog box can be accessed from the Project menu. For more information, see.
To add a project reference
In Solution Explorer, select the project.
On the Project menu, choose Add Reference.
The Add Reference dialog box opens.
Select the tab indicating the type of component you want to reference.
In the top pane, select the component you want to reference, and then click the Select button. Press CTRL while clicking to select multiple components.
If the component you are looking for is not in the list, you may locate it using the Browse button.
Click OK when you have selected all the components you need.
Selected references will appear under the References node of the project.
To remove a project reference
In Solution Explorer, right-click the reference in the References node, and select Remove from the shortcut menu.