Howdy TOTA! (sorry...too longa name!)
Your enclosure need input and exhaust fans, running 24/7. Plants must have fresh air tor eplenish the Co2 in the box. You can use smaller computer fans (either 120V or 12V with a transformer). One a the bottom side for intake, and exhaust on the upper side (or top) for exhaust.
As for the odor, you have little to worry about until you start them into flower. I would suggest the OdorSok or a like unit, they work great for small grows and allow near -0- aroma to escape.
Out in that shed it is going to get blazing hot some mid-summer...this might be an issue, so the more air you can get into the shed/enclosure, the better.
ISO
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The Essence of Compassion
"Resolve to be tender with the young, Compassionate with the aged,
Sympathetic with the striving and tolerant of the weak and wrong......
...... because sometime in your life you have been guilty of all of these."