how to submit a form in asp.net

A form is most often submitted by clicking on a button. The Button server control in ASP.NET has the following format:
<asp:Button id="id" text="label" OnClick="sub" runat="server" />
The id attribute defines a unique name for the button and the text attribute assigns a label to the button. The onClick event handler specifies a named subroutine to execute.
In the following example we declare a Button control in an .aspx file. A button click runs a subroutine which changes the text on the button:
source w3schools.com

what is ASP.NET Web Forms

All server controls must appear within a <form> tag, and the <form> tag must contain the runat="server" attribute. The runat="server" attribute indicates that the form should be processed on the server. It also indicates that the enclosed controls can be accessed by server scripts:
<form runat="server">
...HTML + server controls
</form>
Note: The form is always submitted to the page itself. If you specify an action attribute, it is ignored. If you omit the method attribute, it will be set to method="post" by default. Also, if you do not specify the name and id attributes, they are automatically assigned by ASP.NET.
Note: An .aspx page can only contain ONE <form runat="server"> control!
If you select view source in an .aspx page containing a form with no name, method, action, or id attribute specified, you will see that ASP.NET has added these attributes to the form. It looks something like this:
<form name="_ctl0" method="post" action="page.aspx" id="_ctl0">
...some code
</form>
source w3schools.com

ASP.NET vs. ASP

ASP.NET has better language support, a large set of new controls, XML-based components, and better user authentication.

ASP.NET provides increased performance by running compiled code.

ASP.NET code is not fully backward compatible with ASP.

How Does ASP.NET Work?

• When a browser requests an HTML file, the server returns the file
• When a browser requests an ASP.NET file, IIS passes the request to the ASP.NET engine on the server
• The ASP.NET engine reads the file, line by line, and executes the scripts in the file
• Finally, the ASP.NET file is returned to the browser as plain HTML

What is an ASP.NET File?

• An ASP.NET file is just the same as an HTML file
• An ASP.NET file can contain HTML, XML, and scripts
• Scripts in an ASP.NET file are executed on the server
• An ASP.NET file has the file extension ".aspx"

ASP.NET is NOT ASP?

ASP.NET is the next generation ASP, but it's not an upgraded version of ASP.
ASP.NET is an entirely new technology for server-side scripting. It was written from the ground up and is not backward compatible with classic ASP.
You can read more about the differences between ASP and ASP.NET in the next chapter of this tutorial.
ASP.NET is the major part of the Microsoft's .NET Framework. w3school.com  get more updated knowledge of zaftech.ca

asp.net intro

ASP.NET is the next generation ASP, but it's not an upgraded version of ASP. ASP.NET is an entirely new technology for server-side scripting.

ASP.NET is a part of the Microsoft .NET framework, and a powerful tool for creating dynamic and interactive web pages.