That BP is very high, especially for someone of your age. I'm sure you know, with such dangerously high blood pressure, you are at risk of heart disease and possible early death. Normal BP is 120/80 and stage 1 Hypertension begins at 140/90.
In order to start reducing your blood pressure, you obviously need to look at your diet, cut out bad fats and refined Carbohydrates. You should exercise your heart by doing moderate intensity cardiovascular exercise, so any exercise which increases the heartrate and encourages you to breathe faster.
You could start off with walking for 20 minutes per day, gradually building up to a brisk walk. Cycling and swimming are good too.
If you go to a gym, then treadmill walking, cycling, gentle rowing and cross training are good. For moderate intensity exercise, your heartrate should rise to about 130 beats per minute. At gyms, the machines are equiped with heartrate monitors, but if you are walking or cycling, you can wear a telemetric strap around your chest, it links in with a special watch, which shows your heartrate.
Keep up the moderate intensity exercise until your fitness level increase. Be cautious about doing weights, as weight training can cause the blood pressure to rise. If you do weights in due course, then take your blood pressure before the session and again after, to check that it isn't rising too high, but start off getting your cardiac fitness to a good level before you start weights.
Hope that helps a bit. Good luck.