What do we learn about each of the charecters on stage in the opening stage directions

As the curtain rises, the four Birlings—Arthur, Sybil, Sheila and Eric—are seated at the table with Gerald Croft. Edna, the parlor maid, is clearing the table after dinner. The Birlings have just eaten dessert. They are “celebrating a special occasion” and are “pleased with themselves.”

Arthur -Husband of Sybil, father of Sheila and Eric. Priestley describes him as a "heavy-looking man" in his mid-fifties, with easy manners but "rather provincial in his speech.

Sheila-Priestley describes her as "a pretty girl in her early twenties, very pleased with life and rather excited," which is precisely how she comes across in the first act of the play.

Sybil Birling- Priestley has her "about fifty, a rather cold woman," and--significantly--her husband's "social superior." Sybil is, like her husband, a woman of some public influecnce, sitting on charity organizations and having been married two years ago to the Lord Mayor.

Eric Birling-Eric is in his "early twenties, not quite at ease, half shy, half assertive" and, we discover very early in the play, has a drinking problem.

Gerald Croft-He is, Priestley says, "an attractive chap about thirty ... very much the easy well-bred young-man-about-town."