You combine the components and speak the necessary words and touch the ground. A wave of fire radiates out from your location. everyone within 40ft of you makes a DEX saving throw. If they are within 10ft, they have disadvantage, and if they are between 30ft and 40ft, they have advantage. A failed save takes 12d6 fire damage, and a successful save takes half damage. 
At higher levels: for every level above 5th level, add 1d6 fire damage.