I need to take photo's indoors tomorrow night

[alacrity]

Going by my past experience I am not very good at getting the light right yet. I am going to a football ball and would like to take pictures of couples and candid's of people having fun on the dance floor etc. There will not be great lighting and I am not very keen on my flash. Do I use my flash for the couples shots anyway and if so how does that affect my f stop settings? And drop the f stop for candid shots with no flash if people are at a distance because the flash is very bad at a distance?
Thanks:)

[ricktas]

rear curtain or second sync flash (different names for the same thing) can create really interesting results for dancefloor photography. Look up in your manual, how to set your flash to that option.