Hi Tony, yup that is normal when you draw an ellipse that it goes all the way around.

If you only want to keep a part of an Ellipse, you need to cut the ellipse up into pieces - for that draw in a line that divides the ellipse and then use the Edit > Trim tool to cut the ellipse with the line.

See here for some more details about how the Trim command works:
http://moi3d.com/2.0/docs/moi_command_reference4.htm#trim

Let me know if you are still stuck using it - basically all you do is draw in a line that goes through the ellipse, then select your ellipse and run the Trim command, then pick which piece of the ellipse you want to discard.

- Michael