Anchor it in opposite direction you intend to bend it down. This should be fairly low on trunk (apical meristem).
Bend between axillary growth, so that each can grow vertically.
Try to shape and bend it with fingers, first. Get it in a good shape by bending in multiple spots that are close together. it doesn't have to be 90-degrees at one point, but you want to approach or reach horizontal above the bend on apical meristem.
The restraint - tie, twist ties, whatever - just holds back hyrdostatic pressure. You may need one to prevent an arch forming.
The more even it is, the more even the growth can be. Height of the axillary growth will have a say about dominance too. Bend things down and other shoots will catch up quickly.