socref,

Go to continental.com, click the "Fares and Reservations" button in the bottom left of your screen, then click "Member Login" in the upper right quarter of the next screen. Login with your eservice name and password, then click "My Itineraries" in the upper right quarter of the next screen. You will be presented with a list of your itineraries. Click one to view it, and you will see the new option.

If you have purchased itineraries with Continental that are not visible, click "add a purchased itinerary" on the same screen to add it (it's in real tiny letters).

Hopefully Continental will re-design their awful web site one of these days so that one can login from the home page.