Year 2 and subsequent years
In spring, train the second tier of branches the same way you did the first tier in Year 1. Continue to cut back any competing lateral growth from the leader and the arms to only three buds. This will produce more fruiting spurs.
Once you've trained as many tiers as desired (four to six is average), and the support frame is covered in branches, cut back any new growth that forms at the tips of the arms and prune out the vertical central leader so it's flush with the highest tier.
How to - Techniques
How to espalier a tree
Train fruiting trees, vines and bushes for a bountiful harvest in tight spaces