please stop smoking ~ (담배 끊으세요)
담배 끊으세요 ~ "please stop smoking"
담배 피지 마세요 ~ "don't smoke"
흡연은 위험하다 ~ "smoking is harmful/dangerous"

i learned 끊다 and 피다 but i still don't know how to write. ㅠㅠ
i think i am scared to make a mistake and make myself look stupid.
i want to know how can i write...........

I am a smoker.
Do you smoke?
May I smoke here?
Did you quit smoking?

Question

please stop smoking ~ (담배 끊으세요)
담배 끊으세요      ~ "please stop smoking"
담배 피지 마세요 ~ "don't smoke"
흡연은 위험하다  ~ "smoking is harmful/dangerous"

i learned 끊다 and 피다 but i still don't know how to write. ㅠㅠ
i think i am scared to make a mistake and make myself look stupid.
i want to know how can i write...........

I am a smoker.
Do you smoke?
May I smoke here?
Did you quit smoking?

Answer

I am a smoker. ( 저는 흡연자 입니다.)
Do you smoke? ( 담배 피우세요? )
May I smoke here? ( 여기서 담배 좀 피워도 될까요?)
Did you quit smoking?( 당신은 당배(를) 끊었습니까?)

Answer

저는 흡연자입니다 is written in a literary style. 
Don't smoke. 담배 피지/피우지(both right) 마세요. 
I am a smoker. 저 담배 피워요. 
Did you quit smoking? 담배 끊었어요? / 담배 끊으셨어요?(more honorific) 

저 술 끊었어요. I quit drinking alcohol. 
담배 피우는 사람 싫어해요. I hate smokers.