I have spot heated with a torch to take bows out of steel! But for me, I have about a 50/50 chance getting the result I want . I bet some steel fabricators here can give better advice but heat will work.
Try placing it on a bench with the bow up and block the ends up on wood blocks and draw the center down with a clamp a bit past what you want and give it a smack with a hammer, the shock from the hammer will usually do the trick. It may take a little trial and error but I prefer cold straightening when possible.
Grandma always said "if ya can't be handsome ya better at least be handy"
Small steps. What parts of the smoker are the pieces for? In other words will it show/matter they have a slight bow? Presuming it is slight.
Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.
Whether you think that you can, or that you can't, you are usually right. Henry Ford