how are you explaining? first of all if you are not using the language of a child you will go nowhere. you might as well speak washo. second of all they have to understand you. so telling a 2 year old is not the same as telling a 20 year old. to make it equal you need to repeat, repeat, repeat multiple times a day for at least 2 weeks before your 2 year old gets it.
that's why the first 3 years you are either a pantomime clown as i was or the greatest diverter in town. you either make a game out of it, or you remove the child.
Truth be told, I am explaining nothing yet as my girl is 4 and a half months and my first graders, by and large, already had their behavior in place by the time they got to me.