Help please! i don't know when will the nicotine cravings stop?

It can go on for: some time, at least several weeks if not a month or more. If the cravings are severe, getting in the way of your life, or making it likely you will relapse to tobacco, I would strongly consider nicotine replacement therapy, either with patches in tapering doses (21 mg to 14 mg to 7 mg every 1-2 weeks), or just use gum/lozenges when they are bad. Congrats on quitting, and try to stay quit.