Fruit tree stakes/supports should not be any taller than about 120cm/4ft, and around 50cm of the stake should be below the ground, leaving approx. 70cm above ground level to support the tree.
The tree tie should then be fixed no more than 2.5cm/1in below the top of the stake, in the form of a figure-8. To make the figure-8, the vertical ribs on the tree tie should be on the inside, against the bark of the tree (they are there to allow room for expansion as the tree grows). The pointed end should then be threaded right through the first slot in the tie and tightened onto the tree, though not too much. The length of the tie that has been threaded through should now be looped round the stake and threaded back through the second (outer) slot in the tree tie, fully tightened and locked off using the teeth in the pointed end of the tie.
The crossover acts as a spacer between the tree and the stake, so that when the tree moves in the wind, it cannot rub against the top of the stake. If it does, it will quickly open up a nasty wound through the bark allowing canker to infect the trunk.
The top of the tree above the stake should be allowed to flex freely in the wind, this is one of the processes by which tree trunks strengthen themselves. It is also often a good idea to cut back the main shoot to the height at which you want the head of the tree to form. This is usually either at about 75cm above ground for a bush tree (so that in later years most of the fruit will be produced within easy reach), or higher up, at around 135cm/4ft 6in for a half-standard (this is worth considering if for instance the tree is being planted in a lawn to be mown around with a ride-on mower), though steps will eventually be needed to pick the fruit.