Screw the adaptor into the spark plug hole on the cylinder nearest the cambelt, fit the dial so it has a bit of travel both ways.
Remove at least one spark plug from the other cylinders or you will find it really hard to turn the engine over.
As you turn the crank the needle on the dial gauge will spin round as the piston rises, then spins the other way once its passed TDC and is descending.
There is a mark on the crank that points to a mark on the block that roughly indicates where TDC is, so you can get roughly in the right area, then use the dial gauge to get it bang on.
There are 2 TDCs (exhaust and intake) and only one of these the cam locks will fit on, if the cam locks dont fit, give it one more rotation.
I did look on youtube for a guide, as almost everything has at least 1 video about it, but I couldnt find a good one!
Oh, if you take the balance belt pulley off you can turn the crank with a 19mm socket on a ratchet