Refer the article.

Contact Us Form with Rich TextBox in ASP.Net

Or use below from html page.

<form action="mailto:Waghmare@gmail.com" method="post" enctype="text/plain">
    Name: <input type="text" name="name"><br/>
    E-mail: <input type="text" name="mail"><br/>    
    <input type="submit" value="Send Email">
</form>