what does "fancy people"mean?
Either the image came more naturally, or the beer helped it along.
“They threw some big parties at Bluff House,” Stoney told him. “Fancy people would come up from Boston, New York, Phillydelphia and where-not. They’d have the house lit up like a Roman candle, with people gliding along the terraces in their white tuxes and evening gowns.
“Made a hell of a picture,” Stoney said, and downed his bump.
“Yeah. I bet it did.”2. what does "where-not"mean?
3. what does "lit up like a Roman candle"mean? does "Roman candle"have any special meaning here?

Question

what does "fancy people"mean?
Either the image came more naturally, or the beer helped it along. 
“They threw some big parties at Bluff House,” Stoney told him. “Fancy people would come up from Boston, New York, Phillydelphia and where-not. They’d have the house lit up like a Roman candle, with people gliding along the terraces in their white tuxes and evening gowns. 
“Made a hell of a picture,” Stoney said, and downed his bump. 
“Yeah. I bet it did.”2. what does "where-not"mean?
3. what does "lit up like a Roman candle"mean? does "Roman candle"have any special meaning here?

Answer

Here "fancy people" is being used as a slightly disdainful term for people who are wealthier and probably consider themselves more civilized than the speaker.

Where-not is used as a slang term for "or wherever", "other places I dont care enough to name specifically".

Roman candles is a reference to a type of firework, but when traced back it refers to when ancient roman citizens in their anti-christian era would cover their pious prisoners in wax and light them on fire. :P Pretty gruesome, but the firework is named that because of the screaming sound it makes when you light it.

Overall it sounds like this character has a low opinion of the "Fancy people" he is talking about.

Answer

'Fancy people' can refer to rich people. It usually can refers to people who always dress in formal instead of casual  clothing. Their lifestyle seems very sophisticated.

'Where-not' means 'and other places as well" or 'etc'. The author didn't want to name all the places. So, they wrote 'and where-not'.

Roman Candles are a type of firework.  This video shows Roman Candles:  https://www.youtube.com/watch?v=UXTmuPtFZw8

Answer

'Fancy people' would mean rich, well dressed people.
'Where-not' would be the same as 'where-ever', similar to 'what-not'.
A 'roman candle' is a type of firework, that sprays a column of bright sparks.