I thought I wouldn't have too much of a problem but I can't figure out some basics like how to home my machine.
Here are some basics about me and my setup to show I'm not entirely clueless (although it feels like it).

I just bought a Taig CNC Mill and playing with Mach 3.
I'm used to Gcode and things like homing/limit switches from building a custom delta 3D printer, plus various constructions of generic multi-axis motion control over the years.  I am NOT familiar with using a CNC interface like Mach.  Usually I construct a custom control interface with Labview or other software and all interfacing is with gcode over a serial port.  My printer's control board has implemented all parameters, controls, and commands in gcode, which makes it very easy to use.

I'm used to homing my printer with a gcode macro that moves the stages to some limit switches, backs off, approaches more slowly and stops again at the switch closure, then define that as zero, all with nothing but gcodes (delta printers don't have x or y limit switches).   In the CNC world that would be used to define machine coordinates (G92, right?), which would then be the coor system I would use to define the soft limits (zero to some length of my stage). In this case the negative direction limit switch would be defined as zero.

However, I can't even find a button to start a homing operation. 
Where am I going wrong here?
thanks

You could try the 'Ref All Home' button on the program screen.

In the CNC world that would be used to define machine coordinates (G92, right?), which would then be the coor system I would use to define the soft limits (zero to some length of my stage). In this case the negative direction limit switch would be defined as zero.

Machine Coordinates are G53, and soft limits are relative to G53 coordinates.