First thing… did you cut out a second crescent moon for the base? What you should have is two crescent moons (one with windows and one without).
When it cuts, there are certain pieces you don’t need. You’ll keep the circles with the dates, as well as the black pieces. The red pieces you can discard.
On the bottom, you need to glue the separators (the black pieces shown above) so that they can create a path for the date circles to move through. (see photo)
Once the separators are in place, you would put the circles with the dates in place, and then glue the top to the outer separator and inner ones.