This article will explain how to select the new version of ASP.net 4.0.
Scroll down to the Web Hosting section, select the relevant domain name from the drop-down box and click on the Manage button.
Click on the Manage IIS Application Pools link in the Web Tools section./p>
Select the version of ASP.NET using the drop down list in the Application Pool Managed Runtime Version section and click on the Update Now to save the change.
Please Note: We recommend that you back up your website files prior to upgrading from version 2.0 v to 4.0.