Just having a little fun!
There's a couple of ways to do it. One way is to remove all the screws and join the rails together with clamps and try to bend. I thought that was the way to do it, but you quickly find that the section ends do not want to line up with the ends of the tie sections, and you find yourself trying to trim EVERY rail end.
So, what I did was remove all but the center screw on each rail of each curved section. Then I connected 2 sections together. Now I bend this set of 2. There's enough give to let this work easily, and the screws left in place will keep the rails from trying to slide every which way.
So, bend up enough "Sets of 2" to do your curve. Now you connect these sections and if the change in radius is not huge, you will only have to cut one rail not both when joining these sets.
It may sound complex, but it saves you cutting a lot of rail, and speeds up the process.
Regards, Greg