How do you set a GE outdoor timer to go on at a certain time and shut off 6 hrs later? Does the on/ off button have to be in a certain position, and how to I set the dial?

SOURCE: intermatic hb65r residual outdoor timer

Here is the instruction manual for your model:

HB65R Timer

Hope this helps!

Also consult this website for sunrise, sunset information for your area:

Sunrise sunset calendar

SOURCE: resetting outdoor light timer

I would unplug the timer. Change the setting to 6 hours then plug back in.

SOURCE: I have a Woods TM1710

Woods timers and manuals
Woods TM1710 shows at page bottom, and does not have online manual that I can find
http://waterheatertimer.org/Woods-timers-and-manuals.html

TH1710 is a promotional timer for outdoor use.
TD series and TM series timers are evidently sold at a price point, and not made with same features as more expensive timers.

That being said, TM1710 has a dial that rotates as time passes.
Poor image quality is hard to make out, but dial looks like 12 hour.
If this is true, then time programs repeat each 12 hours.
Set timer and the lights turn on-off during am hours, and then cycle repeats for pm hours.
Kinda silly to make 12-hour outdoor repeat timer since you want outdoor lights ON during pm but not am. But cheap prices sway we shoppers who later discover a saw horse that is supposed to balance on 2 legs.

To set ON-OFF times, there are segments located around outer edge of dial.
Pull segments up or leave them pushed down to set ON-OFF.
Most timers are OFF during hours when segments are pulled up, and ON when segments down, but this timer may be opposite.

Manual override is button or switch that overrides timer functions and turns light ON full time.
Again poor image quality makes it impossible to see manual override, but it looks like manual override is white button to lower right of dial.
If that button is manual override, then it appears to rotate.
Usually you set override one direction to override, and other direction for timer to operate