Hey Mike ,
the rails are cut with a slot in the middle , you have options
1)small ball head (usually found on rc cars ) you attach the ball to a wood or plastic flat sheet and its attaches to the inside of the canopy and it will slide into and thru the rail .
2)You can use plastic or aluminum T frame rails , again bought at the hobby shop and it will slide (size appropriate ) thru the slot that is cut in the brass rails
Hope this helps