Hallel is the part of the seder where we praise Hashem. Pesach is the only רגל that we say Hallel shalem on the first 2 days. The dvar torah is about the prayer of Hallel. Hallel is being said at the last part of the Haggadah. We say it after the seudah on a full stomach. There are places where it is customary to recite the entire Hallel communally and to recite the blessings beforehand and afterwards on the first night of Pesach after the Evening Service. It is similarly recited on the second night of Pesach. This custom is not practiced in these regions, for we do not recite Hallel at all in the synagogue on this night. 

This idea is from chabad.org


haggadah Section: Hallel