C# .NET - Copy text from Texbox control to the webpage

I'm using ' System.Windows.Forms.WebBrowser'

Loaded webpage -Done.
Query -  How can I copy the text from Textbox to the webpage on WebBrowser control (say "google.com' input box)?

Using something like this, 
WebBrowser1.Document.GetElementById("gbqfq").InnerText = txtInput.Text

Try this one

http://stackoverflow.com/questions/12057985/c-sharp-using-webbrowser-control-and-need-to-access-dom-elements