The first code sheet can be located on several boxes up near PaP. However the second Code is in the entry to the Zepplin.
-On the other side from where you enter there is a steaming valve to the right of the main door. ---Shoot that with a PaPed weapon and it'll start the mini EE.
-After that the steam moves to different valves across the zepplin with a few locations being inside barriers and one of them being right next to where the Code sheet is.
-I believe its after 5 or 6 valves have been shot you can press a button on the other side of the zepplin spawn that releases the pressure which blows the code out of the zepplin.
-The code can then be found on a box to the left side of spawn near a barrier
-After you have both code sheets go back into the zepplin and put them into the slots next to the closed door in the main room of the zepplin.
-Then on the top floor, if youre looking away from PaP go to the left side and before you enter the spawn room to your left should be a control panel which lets you start a lock down. (its a bit overwhelming so be prepared)
-After that the closed door should open and you can pick up a flare gun which works as both a g-strike and monkey bomb
-In that small room there is also a lever which I have yet to figure out what it can do
-If you need me to clarify anything ask and I will get back to you, I hope this helped!