This is such a complex process, that the best way to work it out, is to keep trying. I would need to write a very large tutorial in order to make something like this clear. But the one tip I can give, and have given to many others before; Use the Vanilla Textures to see where and how it aligns. One of the Desert textures has good polar areas where you can see where the 'Pole' ends and the unread section begins.
For the Night Side, what? It should be pretty much 90-95% black, with city lights showing over the blackness.
While I'm here though, you should really have a go at making your own city lights on the night side. They are not hard to do, and I think they are the best part of making a texture. Give them a glow, make them strange and crazy colours (I usually use yellow, but am experimenting with other colours now), wrap them round coast lines, at mouths of rivers, places where you would
expect to see a city, not in a random places with no rhyme or rhythm.
Any way, good luck, and keep at it