Bend the base support in the very middle to give enough room to enter the opposite side of one of the ring supports. Initially you will probably have multiple base supports in one slot in the ring, that's ok. It makes it easier to separate later. Then separate the base support to place the base supports into the other two slots on one side. This should allow you to make the middle one straight as seen above.
Next separate the base supports on the opposite side to enter the slots. You will need to bend them slightly to get them to fit in. Once in you can straighten the cardstock. Now the base is complete.
Once it bottoms out slide the top of the ring together to fit into the top cutout.
Hold the ABC joined piece together as if they are on and bend it slightly along the cut lines in the snow man. Place ring D (D and E are identical it doesn't matter which is which) into the two cutouts in the top of the joint section and ring E into the bottom two cutouts, to create what is seen above.
Separate the sides of the joint ABC to place them in the cutouts in ring D and E. It's best to complete one side at a time so that the center can straighten out before you separate the other side.
Lastly repeat the last step for the other side to complete the sphere.