You can paste text into the RichTextBox but it will not be formatted "automatically" - see comment from OriginalGriff.
Once you have applied the formatting you can save the text with formatting to the database by using the RichTextBox.
Rtf
property
reference information[
^]
[Edit]
You can find examples of formatting the richtextbox text
at dotnetcurry[
^] for example.
Or you could do the formatting in Word before you cut&paste
The rich text box will do the conversion to rtf for you
[/Edit]