I have this that's light but it's like a dry cough but flem keeps coming up? what do i do to stop coughing?

Depends...: Treatment of any cough depends on the etiology. If it has been present for 3 weeks or more, it may be due to bronchospasm of any cause, gerd, post-nasal drip or a combination of these factors. If the cough is of less duration, acute bronchitis is a possibility. You will need to see your doctor for diagnosis and then treatment since all of these have different treatments. If you smoke, quit asap!