Grow Your Own Magazine

Have just been reading The October fruit garden in GYO and it says fruit trees over 4 years old should be grease banded. Can anyone tell me how I go about doing this?

Go to your nearest Garden Centre and buy a packet.
You can make your own, but it is probably not worth the effort.
All that a grease band does is to trap various apple pests as they make their way up or down the tree. It is just a band of grease impregnated cloth, sometimes with insecticide in it too, sometimes not, depends on the variety.
The insects get trapped in the goo.
Once all the fruit is picked and the leaves have fallen you should also spray or wash down the trees with a Winter Wash. There are organic versions of these available now.