Well . . . this could be long which I hate, so I will keep this short and hope it leads you down the bunny trail.

 There are two AP stations on the 727
1) Is called "Autopilot Panel"  which sits bellow the throttles and radio / Nav radio stack.

2) is called "FLIGHT DIRECTOR CONTROLS" which sits above the throttles on the left and right.

 To work the AP . . .
Once lined up for T/O I assume that your heading indicator is lined up with the runway or the heading that ATC issued.  I would then go to the  "Autopilot Panel" panel and make sure your heading selector is up to activate and the knob above is on "B".  On the "FLIGHT DIRECTOR CONTROLS" panel turn the knob to HDG. Make sure your Nav radio is tuned to the first VOR.
 Once airborne and in good steady rate of climb,  flick the two switches on "Autopilot Panel" called "ELV" and I forget name, but there side-by-side, but go ahead and flick up to engage.  Once your vectored to your first VOR or ADF and your "Radio Magnetic Indicator (RMI) is reading your signal, turn both knobs from "Autopilot Panel" and "FLIGHT DIRECTOR CONTROLS" to LOC/VOR and turn off the HDG on your "Autopilot Panel" and your are set on AP.

  I hope this helps!