what does stacey try to get

He ran away to work in the cane fields.

What were they building???

I don't see any references to the family "building" anything..... their cotton crop looks great, but he knows that they won't have enough money after the bills have been paid. Neither Mama or Papa have been making any money....... they won't make it on the crop alone, and Stacey understand that he'll have to go out and make some money in order for the family to have a chance at keeping their land.