I agree with JayG regarding runner beans, also for French beans that are pole beans. the vertical strings could be something relatively light, like mason's twine, and doesn't need to be straight up-and-down. I'd zig-zag twine between the lowest horizontal on the support in your photo, go up to the top, with a twist around each horizontal in-between, reverse course and go back down again, and keep going.
Broad beans are generally not grown here, so I have no opinions on that, other than to say, follow JayG's advice.