Chalk out the curve on the floor and bend it in a vice a bit at a time , if there is a fabricators near to you with a set of bending rolls they might do it for you.
Personally, I think you'll have an easier time clamping one end down, or welding it to the bench, and pulling the other end round one continuous curved former. It gives a single smooth curve rather than a series of discrete bends and is very quick and easy to achieve.
Up to around 25mm square, manual bending around a former is OK, but I read the discription in the link and they are fabricated out of 40mm squ. I made myself a power roller bender for this and 50mmsqu. I would suggest you find some one with the kit.
KF
Flypress. Top tool is a simple curved profile, bottom tool is a couple of pieces of tube say 50mm dia. welded to a baseplate about 250mm apart. Bump it through to get just about any radius you want.