"Can" is expressed with "abilmek, ebilmek" suffix in Turkish. "I can do it!" "Bunu yapabilirim!" (Here it's abilmek because of vowel harmony) "I can come with you." "Seninle gelebilirim." (Here, it's ebilmek again vowel harmony.) Must and have to are the same things in Turkish. It's expressed with "-meli, -malı" suffixes. "You have to come." "Gelmek zorundasın." "You must stop." "(Sen) durmalısın." Also you can use "zorundayım" it's basically "verb + zorundayım" "I have to sleep." "Uyumak zorundayım." If is "eğer" "If you're going to visit us, bring your friend too." "Eğer bizi ziyaret edeceksen, arkadaşını da getir." I hope these help, have a nice day. :)