I'm soon 18 and don't poop everyday. basically i poop only once in a week. please help me?

Eat better: Fiber, fluids, fruits avoid chronic laxatives, narcotics.

Constipation: It'd be advisable for you to see a doc to determine the cause(s) of your constipation. This is important as the successful treatment of it relies upon the correct diagnosis. General principles advisable in constipation of any cause are - increase in fluid and fiber intake, increase in physical activity. Avoid food known to contribute to it - breads and like products. May try otc MiraLAX (polyethylene glycol) to start.

May be normal: Everyone does not have a bowel movement every day although that is probably ideal. One theory of the cause of colon cancer is stasis of stool containing carcinogens with them having a longer time in contact with the colon wall. You might try getting more fiber in your diet and supplement that with natural laxatives such as metamucil, drink lots if water and get lots of exercise such as walking.