In Solution Explorer, select the DLL project.

On the View menu, choose Property Pages.

In the ProjectProperty Pages window, in the Configuration drop-down list, choose Debug.

Open the Configuration Properties folder, and select the Debugging category.

In the Debugger to launch list, choose Local Windows Debugger or Remote Windows Debugger.

In the Command or Remote Command box, click the drop-down arrow, and select Browse from the list to locate the application.Alternatively, type the path and name of the application.

Type any necessary program arguments in the Command Arguments box.

In Solution Explorer, select the DLL project.

On the View menu, choose Property Pages.

In the ProjectProperty Pages window, in the Configuration drop-down list, choose Debug.

Click the Debug tab.

You can start the application by either doing the following:

1. Set the Start Action to Start external program.

2. In the Start external program box, click the ellipsis button to browse for the application.

3. Enter any necessary program arguments in the Command Line Arguments box.

Or, you can invoke an application at a URL. (You might want to do this if you are debugging a managed DLL used by a local ASP.NET application.)

1. Under Start Action, select the Start browser in URL: radio button.

2. In the adjoining text box, type the URL.

In Solution Explorer, select the DLL project.

Set breakpoints as needed.

Enter the name and location of the calling application in the ProjectProperty Pages dialog box or window. If the application is a console application, fill in the command line arguments, if it is necessary.