Just like a brochure has sections, you'd create a new post for attachments of that section.
We're trying to make a modern forum out of an ancient code base here, and it's not a brochure system; I'm sure you could hire a private developer to make you any type of system you'd want, but for a forum we have a staple set of functionality that we really need to work on, versus fluffing things up like competing software.