Thank you for writing.
The referred tutorial is not applicable for the Telerik UI for WinForms suite. RadAutoCompleteBox
allows the end-user to easily fill-in text thanks to auto-complete functionality and tokens of text. The suggestions come from the applied AutoCompleteDataSource
Additional information for RadAutoCompleteBox
is available here: http://docs.telerik.com/devtools/winforms/editors/autocompletebox/autocompletebox
I hope this information helps. Should you have further questions I would be glad to help.