The rep button is the little star next to the triangle on the bottom ribbon of the post. It allows you to give a positive or negative rep to the poster.
You probably did not get this problem from the outdoor stored soil. Fungus gnats lay their eggs in soils that do not dry out on top. Too frequent watering is usually the culprit. Let the soil dry on top between watering and you will not have a problem with this pest. As others have said these insects are fungus gnats not fruit fly's. This can be controlled with a soil drench of Bacillus thuringensis (Bt). They are not only flying around the pot and plant, but the larvae is also in the soil and must be controlled also.
Hopefully this electronic pest controller will be effective on many different pests of MJ.