The candle itself, unlit, represents Earth. When touched with Fire, the candle melts, producing wax (representing WATER), and smokes (AIR).
You will need a new candle, the color of your choice. Choose something that corresponds with the type of spell you wish to perform.
Consecrate the candle and carve a pentagram on it.
Say:
Upon this candle I will write
What I receive of thee this night,
Grant me what I wish you to do;
I dedicate this rite to you.
I trust that you will grant this boon,
O lovely Goddess of the Moon.
This type of candle spell works well with any ritual.
Simply, charge the candle with the energy raised to do your wish.