offering before or after summoning?

[derikgsthreesixs23]

I'm going to summon a demon tomorrow night.I'm ready. But do I need to offer something in return before we start or after were done with everything? And the demon I'm going to summon, her candle is red but I only have black and blue candles. Can I offer her a black or blue one? And can anyone give me any extra tips because I'm nervouse and I want everything to go perfect. Thanks