You will need a timing light to start with. I prefer the ones that take batteries.....no induced signal from the car battery that way. But I use mine on lots of different vehicles including motorbikes, so others will have other opinions on that. Plus the R33's have the battery in the boot so.....hard to use one that doesn't have its own power anyway.
Most youtube clips show the ones that hook up to your cars battery.
Car has to be warm and idling at 650 rpm, every mark is 5 degrees, you need to be at the 4th mark [three gaps] for RB25, 5th mark for GTR, [check the sticker on your bonnet, should have the degrees you need], loosen the three bolts holding the CAS and turn this to adjust the timing - only loosen as much as you need, it shouldn't be flopping. Turn off car, tighten bolts on CAS, start car and check. Kick back and have a beer!!!
Long version............google or youtube.