After the Seder meal is eaten and the benchen, the Grace after Meals, is recited, a fourth cup of wine is filled, and the following actions are performed:
-According to the custom of many people, an additional fifth cup is poured for Elijah,
-A door is opened,
-Some people place a picture at the door entrance showing Elijah blowing a shofar announcing the arrival of the messiah,
-Some families have one of the participants rush out of the door and then reappear as Elijah,
-Some families also exclaim baruch haba, baruch haba, “welcome welcome,” when the door is opened,
-A paragraph that originated in the Middle Ages containing three parts, each of which say the same thing, is then recited,
(Rabbi Dr. Israel Drazin]