Install MSD 6AL Ignition control with FiTech (new to all this!)

If you don't have the full fitech instructions you should download from fitech website. They should be there. Same for the MSD box from them. Same for command center install. It appears from your diagram you have fitech without timing control.

Follow 67Dart273 recommendations above to get your 'run' power. I took mine right off the ignition switch but same thing when ballast is jumpered (and that wiring is closer). I added 15A fuse.

Here is what i did on my 63 for Fitech and similar to your drawing. Mine is Fitech 30002 with MSD 6AL.

Large red wire is main power and gets run direct from battery (or starter). Fitech recommends 25A fuse.
White wire is switched power (see above). This must be on when cranking and running.
Yellow/black goes to your temperature sensor on manifold.
Blue goes to your 'tach out' (gray wire) from your MSD box. Keep this one separate from other wiring to reduce interference. Sometimes shielding recommended.
Orange goes to positive on your command center.
Purple and green (if you have them) is not used if not controlling timing.
Black is not used.
Last and most difficult is o2 sensor.

You don't mention if the MSD is already installed. But, as 67Dart273 says, the coil gets wired only from the MSD box. Mine is black to negative and orange to positive side of the coil. Distributer is also wired to MSD box if it is a conventional 2 wire one (not HEI) and you are not controlling timing with fitech.

Download some electrical drawings for you car and mark them up as you go.