I don't know what the previous guy was talking about about going through the door after blowing up the crate.
I did it this way: First, like he said, I blew up the crate. Then, I went up on the catwalk and used boxes to get back to the main floor (the one where you start). Next, starting at the entrance to this room, I ran to the door that is set in a recess (I think it's the 4th door from the entrance if you go right) . Anyway, you can just try all of the doors until you find the right one. The correct one will look like the opposite side of the door that the previous guy was talking about. There should be a door that won't open (it's locked from the other side; the locked side is where you could drop down to get some powerups, etc on your way up to the catwalk) with a grate right above it. To the right there will be a HUGE hole in the wall (you can also listen for a burning sound). Go in there and follow all of the doors, etc until you find Lando in the prison. Hope this helps.
Duct Tape is like the Force: it has Light Side and a Dark Side and it binds the galaxy together.