Hi, Jeff
Welcome, Hears a start, We'll help you as much as you need, So Ask Away.
On your printer port cable, Your Step+, Dir+, You can use these pin's, 2 - 9, 1, 14, 16, 17, There (output's).
Most use, "X", 2,3 or 3,2, "Y", 4,5 or 5,4, "Z", 6,7 or 7,6.
Your Step-, Dir-, Use common/Gnd., pin's 18-25 considered to be the same Gnd. connection.
Note: Not all printer ports or Cables use all of them, So connect 18-25 all together.
Hears a link to Getting Started Manual:
http://www.machsupport.com/docs/Mach3Mill_Install_Config.pdfHope this Helps, Chip