curse vs spell?

Would need the evocation of the demon, and a tool for communication, like a mirror would help.

If you are a beginner, you need to learn the basics first, do not, in any case, work with a demon. Never summon what you cannot Banish.
What does the day matter? What does the color of the candle matter? It matters a lot. For your spells to work, first the is the Will to work the spell. Then your have to have the correct Moon phase, the correct day, the correct time etc.
Casting a curse takes more energy than casting a spell, but basically they are the same thing.