If you are using the Data Project Explorer view Debug action, the launch configuration will be created for you and you can skip this and the next step.
If you want to search for all instances of the source file name in the source search path, select the Search for duplicate source files on the path check box. If you select this check box and the debugger finds multiple instances of the file name, you will be prompted by a dialog box to choose the correct source file.
After you have saved a debug launch configuration, you can edit it. For further information about editing debug launch configurations, see the related task.