The way to do this is by copy/pasting the ad code in "Source" mode, in the CK Editor.
This can be done in all pages where CK Editor is used, even the Right or Left Hand Column if the restricted width permits (Ensure the particular ad is not too wide for the RH column ).
Note! The CK Editor will sometimes delete code it thinks is incorrect (mainly javascript, etc.), so if the code disappears next time you update the page, you might need to re-insert it. Keep a copy of the code handy for re-insertion if necessary.
Information on this website is provided in good faith. BusyCMS functions may change from time to time. Specific requirements should be first verified with BusyWeb prior to setup.