In this poem, the "you" is referring to a couple different possible entities. The first is the woman to whom the narrator is speaking, the one that he is enamored with and wants to ask the mysterious "overwhelming question." But it isn't as if he is directly speaking to her; he is speaking to her in his mind, in a hypothetical sort of way. He uses "you" in a hypothetical conversation that he wants to have with her; it is the ideal thing that he would want to say. He wants to show his heart to her, to speak to her of his fears and insecurities; so, in his mind, he puts her there, and takes her on a walk through the ramblings of his mind.
The other possibility for "you" is a generalized, all-encompassing you, referring to anyone that is reading the poem, or to a large group of people to whom he is addressing his thoughts. He says to his audience, "Hey. I have some things to say--want to listen for a bit?" You means you and I as we read the poem. Then, the "I" refers to himself. He is letting us into his mind, and speaks in the first person as he reveals his thoughts.
I hope that helped; good luck!