I found a solution to my problem. Here's the code:
Telerik.Windows.Documents.Model.Table table = new Telerik.Windows.Documents.Model.Table();
Telerik.Windows.Documents.Model.Section section = richeditReport.Document.Sections.ElementAt(0);
Telerik.Windows.Documents.Model.Block firstblock = section.Blocks.ElementAt(0);
if (section != null && firstblock != null)
I was also wondering when the next RadControls version is going to be released and if it's going to include headers and footers for RichTextBox?