Step1:
Download Ajaxtoolkit from 'www.codeplex.com/AjaxControlToolkit'
Step2:
Install from .msi file. You can find Ajaxcontroltoolkit.dll in the installed folder. That is what we need
Step 3:
Take visual studio. Write click on toolbox and add new tab. Give some name.
Then take 'Choose items' and choose 'browse' option from pop up window
Point to our Ajaxcontroltoolkit.dll and click ok.
And accept everything that follows
Step 4:
All controls needed are installed now. Happy coding Nithin :)
Regards, Joby (Please mark as Answered, if i could help you)
www.dotnetcomplete.com