"An auto mechanic" is correct, and "a auto mechanic" is not. "Auto" begins with a vowel - typically, these will be preceded by "an" rather than "a".

enviroment for auto mechanic?

An auto mechanic is a mechanic which specializes in auto repair and repair focused on cars and motorized vehicles. I believe you are meaning a car mechanic also.

No, you do not have to be a boy to be an auto mechanic. Women can also become auto mechanics.

training required for auto mechanic