You posted under T-100 series outdoor timer
If you have different timer, add a comment with timer model number located inside cover.
T-104, T-103, T-101 timer manuals show on following page:
If your timer has R suffix, like T-101R, that means box is Raintight for outdoor use.
T-101R and T-101 mechanisms are identical except for box. T-101 box is indoor use.
Click model number and drop-down menu reveals link to manualhttp://www.intermatic.com/products/timers/mechanical%20time%20switches/24%20hour%20dial.aspx
If you need simple wiring diagrams, and explanation for each T-104, T-103, T-101 timer:http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.htmlHere's how to set Intermatic T100 series timers
Lift and rotate yellow dial until current time lines up with silver pointer.
Silver pointer is stationary at 6 o'clock position.
Put ON-OFF trippers on dial at times you want ON OFF functions.
Minimum on-off is 1 hour because of tripper width.
If timer is not working, add a comment and we'll troubleshoot.
These timers have replacement trippers and clock motors at Graingerhttp://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hiHow timer works
Clock motor, located on back of mechanism, rotates yellow dial.
Trippers on dial push lever that turns power ON and OFF.
Off tripper pushes lever one direction.
ON tripper pushes lever opposite direction.
When lever is pushed, manual override lever clicks back and forth with audible click sound.