Edit/Add Application Settings Dialog Box
Application settings are simple key/value pairs that let you create application-wide values in a central location that can be accessed from anywhere within the Web application. By keeping application settings as part of your configuration in the Web.config file, you can easily change them. The Application settings dialog box on the General tab displays the list of application setting key/value pairs.
The MMC snap-in for ASP.NET works with IIS 6.0 or earlier. The IIS 7.0 administration tool includes the functionality of the ASP.NET MMC tool. For more information, see ASP.NET and IIS Configuration.
The Edit/Add Application Settings dialog box lets you create and edit Web application settings.
You can click Add in the Application settings part of the General tab in the ASP.NET Configuration Settings dialog box to display the Edit/Add Application Settings dialog box. Then, you specify the key and value for the AppSettings property, which are added to the Application settings dialog box and the Web.config file for the Web application.
Similarly, you can select a setting in the Application settings dialog box, and then click Edit. Then, you can change the value of the selected AppSettings property. The changes are added to the Application settings dialog box and the Web.config file for the Web application.
To display the ASP.NET Configuration Settings dialog box from the Microsoft Internet Information Services (IIS) Manager
Open the Properties dialog box for the Web application.
Click ASP.NET, click Edit Configuration, and then click Application.
For information about ASP.NET Configuration Settings, see ASP.NET Configuration Overview