Aerobics. Aerobics like brisk walking, running, or cycling can often help lower blood pressure. If you're not in the habit of exercising, start with an activity at low to moderate intensity a few minutes each day and work up to moderate to vigorous intensity 30 minutes 5 days a week. Also ask your doctor if it's safe for you to do resistance training. That may help as well.
Cardio first! Hypertensives will have an exaggerated BP response to cardio, so start slow. BP responses are even more so with resistance activity, so wait on this.
Aerobic Exercise. The best program to reduce blood pressure is one that causes weight loss through diet and exercise. Each 5% weight loss will reduce systolic BP by about 4 mmhg. Aerobic exercise is the most effective at reducing bp, but any exercise is better than nothing. Swimming is probably the worst for reducing bp.