It sounds like you have a bachelors degree and wish to apply to medical school.
Most medical schools require a bachelors degree and a year's worth of chemistry, ochem, bio, and physics. If, like me, you didn't take those classes the first time around, you can take them at a college and use that to qualify for med school. If you start with general chemistry in a compressed summer program, you can do the whole sequence in one calendar year. Then the next year you can apply, take the MCAT, take biochemistry, whatever.