How can I raise my bp?

Why? "low blood pressure" is a pop / fad / unscientific diagnosis that's dished out especially in europe, generally when a person wants a diagnosis but the physician can find nothing else the matter. Legs should be long enough to reach the ground, BP enough to get blood to the body. Don't treat a number. Stay fit, trim down, do what you can to make friends who are physically fit, and feel good.