The corner is pretty tight, so the chair had to be pretty simple and small, no room for an armchair or anything.
So I found this at the thrift store for $4.00.
I'm thinking it was a restaurant chair or something, that's what it looked like it to me.
After a little paint, and new fabric on the seat:
4. Staple Sides, stretching to make it tight
5. Staple Corners
First staple the corner, stretching the fabric tight.
Then fold each side in and staple.
Put the seat back on and it's a new chair!