As bad as a Doctor's hand-writing eh?
Basically, it's just an electronic switch ...
1st mode is a 1-off that tells it how long to wait until it bursts into life (eg if it's 11pm and you want to capture a 5am sunrise you can tell it to wait 6 hours before doing anything)
2nd mode tells it how long to activate the switch for (if the camera is in bulb mode this becomes your shutterspeed) (in seconds), but if the camera is in eg Av mode just set it to 1 second (with drive set to single) to take a shot.
3rd mode tells it how long to wait until taking the next shot (so if you want to take a shot every minute - and mode 2 is set to 1 second, you need to set mode 3 to 59 seconds)
4th mode just tells it how many times to go through modes 2 & 3 (goes forever if set to 00)
So you could tell it to wait 4 hours 14 minutes and 17 seconds and then take 73 exposures 2 minutes and 18 seconds each, with 1 hour 19 minutes and 53 seconds between them. Pretty powerful eh?
There are a couple of "Gotchas" though -
1. Sometimes you have to remember to give the camera time to do things, like noise reduction
2. If the camera seems unresponsive it's probably because the unit is still trying to hold the shutter release down (press stop on the TC-80N3) (same goes for sliding the manual button to the locked on position).
Hope this helps!
PS: To change settings, just push the thumb wheel in.