air in a 3x5x7ft space

I have this frame and I was thinking about covering it with some hanging curtains. The top would be completely open with light leaks not being an issue. During sleep and the curtains closed, what is an optimum way to get airflow going? I can put a venting tube under the curtain and have it pull or push. Or I can put the tube at the top of the frame and have it just gently blow air in. What do you guys recommend?

go to the market (craigslist)and buy a used door to fit that closet gap ($3.00-$5.00)

install a passive vent at the bottom and silent bathroom type exhaust($12-$20) at the top of the door

good luck