Im a legal resident of the us (green card holder) I was special court martialed in the air force for wrongful use of cocaine I pled guily and was sentenced to six months confinement and a general under honorable discharge. I was wondering if I could still become a citizen. I have no other convictions on my record. I been in the us for eight years I am currently eighteen years old. Also am I in risk of deportation??

Too risky to apply for naturalization now as using/trading narcotic substances is one of the ineligibility list and you might be deported. Keep your record extremely clean for at least 5 more years, no DUI or any criminal record at all, and have immigration attorney handled your case.

Thanks so in five years with a clean record is it possible to be a us citizen at all or that's that prohibit me from becoming a citizen forever. Also I am eligible to join the army active duty can that help my situation at all if I join the military and complete my four years with an honorable discharge?? I really appreciate your help I'm only eighteen and very inexperienced thank you

You need to take each step carefully. Don't apply for citizenship now, immigration may use the drug issue against you and that means deportation.

You must keep your record clean for the next 5 years, no assault charges, robbery, DUI, etc.
File income tax every year even your income is less than the amount required... these documents are required to submit with the application.
Remember you must prove that you have learned your past mistake and now you become clean, a decent & honest person. Go to school, have a secured job, etc.
When you are going to apply for citizenship, don't attempt to do it on your own, get an immigration attorney.

Good luck.