Fruit is produced on two-year-old canes (i.e. the previous season's growth) so, to make things easy, keep this year’s fruiting canes separate from young new canes as the season progresses.
Try tying the new canes in a vertical bunch in the centre (you can keep them tidy by tying them out along the top wire in bunches). Train the fruiting canes along the lower three wires, tying them in with twine.
In autumn, the fruited canes can easily be pruned out from the base after harvesting, and you should then take the bundled-up current year’s canes and train them along the lower wires to make space for next year’s new canes to be bundled in the centre. Alternatively, tie fruiting canes in one direction and the current year’s canes in the other.
Sometimes the fruiting canes are twisted around the wires in patterns to conserve space with very vigorous cultivars such as ‘Himalayan Giant’. Plants with strong, rigid canes that cannot easily be twisted around the wires (e.g. ‘King’s Acre Berry’) can be trained as a fan, with the new growth bunched in the centre, as above. Blackberries and hybrid berries are vigorous. Allow for 20–25 fruiting canes per plant.
Some additional pruning in spring may be needed to remove frost-damaged growth after winter.