just i need to make my ribbon form to be the mdiparent container and when creating childs from it the child window doesn't appear !!

Hi Bishoy,

Thank you for writing.

By default when you create RadRibbonForm it comes with a ribbon on the top, status strip on the bottom and a panel which fills the rest of the space. When you open an MDI child it is shown, but since there is a panel, you cannot see it. Please remove the panel from your form and try again.
 
All the best,
Stefan
the Telerik team