Once your initial guiding lines are in place, dig holes so that the trunk will be about 6 inches from your wall to allow the plants air circulation, and prep the soil as you would normally, adding organic compost and setting plants at the same depth they occupied in their containers. Clip the tops to about 18 inches, and as new growth appears, preserve the best side shoots and the chosen leader and snip the rest. When branches are about a foot long, tie them loosely to wires or eyebolts using twine or another material that won't dig into soft stem tissue. Prune annually, referring to your sketch for shaping, in late winter or early spring, before active growing starts; continue to tie out branches as they develop, loosening old ties so that they don't girdle the branches. Generally, it takes three to four years of pruning to complete the shape of an espalier and, from then on, selective clipping to keep it crisp.
Your reward for this careful collaboration with nature? A lasting piece of garden art, one that's brightened with flowers, frilled with foliage, or laden each year with fruit that's never out of reach.
Shown: Rosy red apples can embellish a simple privacy fence as long as there are anchors on which to tether the branches.