Burning incense in magical ceremony is an ancient image of wonder and power.
Many people love to cleanse, or "smudge," their spaces with an incense such as sage.
In ritual, the smoke from burning gums or resins which correspond to the forces you are working with symbolizes your desire being carried into the causal plane.
Please remember that burning incense indoors can be quite toxic. I recommend burning incense outdoors, or in a very well ventilated area. For indoor rituals, you can use spray perfumes or flower waters as legitimate substitutes for burning incense.
Another alternative to burning incense indoors is to place your incense material into an incense warmer. Some incense warmers use candles, and others are electric. The incense is warmed to a vapor but does not combust so no smoke is produced which makes a warmer a much healthier alternative to burning incense indoors.