Green-colored phlegm = infection, you need to see your doctor for antibiotics. The mucus is coming from your sinuses, or your lungs? That'd be a sinus infection, or bronchitis, or other lung infection, like pneumonia. Wherever the phlegm is coming from -- same answer -- it's an infection & you need to make a doctor's app't. Feel better soon... :)
If you are coughing, you could have bronchitis. Any other color than clear phlegm is a sign of infection, green indicates a bad infection. Time to see the doctor for an exam and antibiotics. I promise you, no home remedy or OTC cold remedies will clear-up what ails you. Hope you feel better soon.