Hello Pradeep Enugala,
Thank you for writing.
In order to apply custom settings to the application button, you need to create a theme for RadApplicationMenu. It is the first control in VisualStyleBuilder.
RadRibbonForm does not currently support setting a background image through a theme. You can however add a panel to your form and set a background image to it instead.
Please write again if you have other questions.
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items.