I am stuck in Helgen with my hands tied behind my back. ?? and how do I get my hands untied?

Follow the story.

Basically though, you run through most of the town till you have to choose between going with the imperial dude or the stormcloak dude. Either one will untie you.

Sorry-guess I did not make myself clear. I just got of the wagon and am still a prisoner. They are about to chop off my head when the dragon shows up and mayhem ensues. I run into the open tower and try to run up the steps but the stairs collapse and I can't get any farther. So I go back downstairs where some people are tending the wounded and no one talks to me or even sees me. I go out side and the guards are trying to shoot down the dragon and ignoring me. I see no way to get out of there. Now what? My hands are still tied.

Turn right where the dragon bashes the wall and fall through the building.