Prepare yourself for a standard back squat with the bar behind the neck (always ask a trainer for help if you're unsure of the technique). (womenshealthandfitness.com.au)
The below muscle groups are primarily targeted when performing the low bar back squat, in no specific order. (rawbarrel.com)
But before I discuss correct squat technique I'll describe the two types of barbell back squat that you could do. (whatreallybuildsmuscle.com)