After installing the kit, you need to go to the Site Collection settings and activate the SPRadGrid feature and all the others that you need. SPRadGrid, SPRadListView and SPRadScheduler web parts are installed as site collection features whereas RadEditor features are deployed on a site level.
Hope it helps.
the Telerik team
Learn how the Telerik controls can be integrated in SharePoint 2007/2010 from this resource
. To watch them in action, explore our online SharePoint 2010