sides for spacing, i put the round part in my right hand and press it up into the top bar joint. i do the same for the other end and the result will be that the rounded sides will be opposite. i then turn the frame upside down and attach the bottom bar using two nails at each joint. i nail the top bar down to the end pieces and nail the bottom bar/bars into the end bars. my final two nails on each frame will be through the end bar into the top bar opposite to where the wedge was removed. this last nail is the most important nail 