OK, am guessing you now have two branches trained horizontally. Allow the bud nearest the original trunk to do its own thing this year, it will automatically form a new leader, prune the others which will attempt to head vertically as well. The pruned new growth will form the basis of your future fruiting spurs. Next winter prune the new leader, ensuring there are two buds beneath it to form your next espaliered pair of branches.
OK, am guessing you now have two branches trained horizontally. Allow the bud nearest the original trunk to do its own thing this year, it will automatically form a new leader, prune the others which will attempt to head vertically as well. The pruned new growth will form the basis of your future fruiting spurs. Next winter prune the new leader, ensuring there are two buds beneath it to form your next espaliered pair of branches.