How to: Add Web Server Controls to a Web Forms Page Using the Web Forms Designer
You add controls to an ASP.NET Web page much the same way you add any HTML element. You can either use a visual designer and add a control from the toolbox, or you can type the element representing the control into the page's markup. This topic covers using the designer. For information about creating controls using by typing markup, see How to: Add Server Controls to an ASP.NET Web Page Using ASP.NET Syntax.
You can also add controls programmatically at run time. For details, see How to: Add Controls to an ASP.NET Web Page Programmatically.
To add a Web server control using the designer
Switch to Design view.
From the Standard tab of the Toolbox, drag the control onto the page.
A glyph () appears on the control in Design view to indicate that it is a server-based control.