Much like his idol, Walt Whitman, Allen Ginsberg usually writes in free verse. His poems aren't structured by a traditional form, like a sonnet or ballad. However, this doesn't mean that his poetry has no structure at all.
There are three important formal features in this poem:
the apostrophe (or the direct address) to Walt Whitman,
the very long lines
the questions that begin many of the lines.
Though the poem doesn't rhyme of have a regular meter, these other formal features hold the poem together and create its own special kind of form. Those long lazy lines have the feel of a wandering thinker, much like our speaker. The apostrophe gives the speaker a chance to speak directly to his poetic heroes—to connect with them in a way he otherwise couldn't. And those questions, well, there's no quicker way to convey a sense of directionless anxiety than asking a bunch of questions in a row. Confused, much, Ginsberg?