On the night of the Seder, the highlight of the Seder is the Mitzvah of Magid. This is the reciting of the Hagadah, which is based on the Pasuk, ‘VeHigadata LiBincha BaYom HaHu Lemor.’ Now from the Halacha it would be permissible for one person to recite the Hagadah, and for everybody around the table to listen as the Ba’al Habayit (head of household) recites it. This was brought down by the Rishonim, among them the Ritba (Rav Yom Tov ben Abraham Asevilli 1250-1330) It’s also the way The Gaon MeVilna followed. This was based on the principal of ‘Shomea KaOhne’e’, that by listening, it is as if you are saying it.
Our custom however, is a little different. We all recite the Hagadah together word by word. From time to time we pause the reading, and the Ba’al Habayit or somebody that is fluent in the story, explains it in English or the language that the people around the Seder understand.
Of course the ‘Ikar’, (the primary part of the Hagadah) which must be explained is the Pesach, the Matzah, and the Marror. We need to convey these three Mitzvot, why we do them, and what happened. The paragraph of ‘Avadim Hayinu LiPharoh BeMitzrayim’, which follows the ‘Ma Nishtana’, should also be explained clearly.
In order to fulfill the Mitzvah of ‘VeHigadata LiBincha’, the father has to tell the story over to his children. It happens too often that the kids go off to sleep right after they recite the ‘Ma Nishtana’. It’s a mistake. ‘Ma Nishtana’ is only the question. The child has to stay up in order to hear the answers. Now sometimes Pesach, Matzah, and Marror is not said until an hour (or later) afterwards, and the child may have lost interest by then. Therefore, if the children are about to lose interest, it is then appropriate to immediately orate the explanations right after the ‘Ma Nishtana’. It is proper to explain to him in English exactly what ‘Avadim Hayinu LiPharoh BeMitzrayim’ means. It is proper to explain at that time what is Pesach, Matzah and Marror. We do this in order to fulfill the Mitzvah of ‘VeHigadata LiBincha’. So if a child goes to sleep, at least the child heard the Ikar.
The ladies must also hear the Hagadah. Actually, they must at least hear the explanation of Pesach, Matzah, Marror in their native language.
One should not lean during the recitation of the Hagadah. One should sit straight and read the Hagadah with fear and trepidation, in order to fulfill the Mitzvah from the Torah. We only lean while eating, during the Seuda, during the drinking of the wine, and the eating of the Matzah. But the Hagadah Shel Pesach or Birkat Hamazon, there is no leaning. We say it sitting up right.