ladder logic program

[arlo f]

i need a three floor elevator program in ladder logic. it is supposed to light up the corresponding lights on a trainer, in any order they are pressed. this is for a class project. i should be able to go from 1st floor to any of the other two, with a 5 second delay between each floor,(ten between one and three)it needs to go either up or down. we are using an AB micrologix 1000 (analog) PLC with RX Logics 500. it also needs to be a continuous program, to where i can continue to go to any floor at any time, no matter how many times it has been used. i have gotten as far as going from one to two, and from two to three, get stuck at this point, could someone please help me on this?