[header] How to steer a horse with only your legs [title] Angle your legs under your hips. [step] If you want to steer with your legs, you'll need to get your legs angled so that you can give your horse this command. Don't maintain a tight grip with your legs around the horse's ribs, as this will lift you out of the saddle and forfeit some of your deep-seat control. 
[substeps] Keep your legs directly under your hips. Your body should be aligned from your ear all the way to your heel.