This is what you should have when you're done. Now ever since the Ent-D Star Trek ships have liked being mostly flat on the bottom, so what we need is to take the bottom of that oblate ellipsoid and flatten it. The first instinct would be to just delete those parts, but that'll actually be inconvenient; you'll see later. What we're going to do is align the lower half to the XZ plane, but first we need to select the entire southern hemisphere of the sphere, including the equator.

To do this, use the "Rect" button underneath "Select." This is your usual draw-a-rectangle-to-select-everything-inside tool.