from the socket...black and white wire attach to 2 yellow wires coming out of the ballast. From the ballast is a black, white and green...these wires go to the plug/outlet...black is one blade, white the other blade and green the ground or rounded prong. If you have any other questions I would contact Hellolights or whoever made/sold your ballast. You get it wired wrong and especially grounded wrong and death could result.
For wiring on your mogul base. The two wires coming from the ballast marked "lamp" in most cases will be connected, one to the shell of the base and the other to the center of the base. If the wires are marked "lamp" and "Common", then the common will go to the shell (or the outside part of the base).
As for grounding, unless the reflector is ("bonded") to your system ground, connecting the green ground wire to the reflector will do nothing.
Now if the ballast comes with 2 grounding wires, one for the ballast supply and one for the base and (or) reflector, then connect it to the shield and it will be grounded through the ballast.
As for the "plug"...your supply for the ballast will probably have 3 wires. Green (ground), Black (hot), and White (neutral). If you haven't noticed this already, most outlets today have three holes in them. Round one is for ground, a skinny blade and a wide blade.
The skinny blade is for the Black wire (hot)
The wide blade is the White wire (neutral)
It is very important to connect them this way. Your electrical system in your house is connected with the White wires (neutral) connected to Earth ground (ground rod outside your house.) This in essence sets up polarity in your electrical system. You should observe this when connecting your stuff to the outlets.
I hope this helps. I hope I did not confuse anyone. This is my living. At least I can help in that respect. If you need anymore information I will be glad to help.