Fans are the best form for training peach, apricot, nectarine, plums and cherries, but you can also train apples and pears as fan shape. They are best trained against a wall or fence.
You need to decide if you want a 2 rib fan, with one branch growing to the left and one to the right, or a palmate fan with several ribs growing. The picture shown here is a palmate fan, with around 5 ribs growing from an initial cut of 40cm from the ground.
Ideally start with a maiden tree. After planting cut the tree down to around 40 - 50 cm, or the height at which you want the first branches to start. If the tree has some small side branching already at this height, you can cut the main stem back to these branches, and shorten the branches themselves to around 5cm. If you have decided on a 2 rib fan, then select just 2 side branches, if you are opting for a palmate fan then select up to 5 branches. If there are no side branches to choose from, then you will just be heading the main stem back to the height you want branches to grow from (approx 40-50cm from the ground).
By early July you should have some growth to work on.
Each rib or new branch should have put on some extension growth from the tip. If it has also develped secondary branches, select one or two that will grow up and one that will grow down to fill the space between the ribs. These can be pinched back to 5 leaves, if they are longer than this. You can now start tying these branches to bamboo canes. The best structure will have horizontal wires every 30 -40cm against the wall/fence, which you can then tie bamboo canes directly to the wires at the angle you choose. The developing branches can then be tied to the canes.
Fans require a fair amount of continued attention! The aim is to allow the tips of the branches to put on extension growth whilst utilising any side branching from these ribs to fill spce on the wall/fence. Pinching out these side shoots through the growing season is necessary to avoid the fan becoming too congested.
Once you have got through the first season of growth, it should become clear how to continue training the fan into the shape you would like!