My profile indicates I am a newbie too, but I used to post on this site and others quite regularly and speaking from that perspective I know that site users aren't keen on doing someone's school projects at the last minute for them. It isn't as if this site is networked to a bunch of people sitting and waiting for that kind of thing.
Having said that, and I certainly didn't mean to sound rude and perhaps you have an urgent security matter that requires a McGyver security system installed tonight? If that is the case we wouldn't want you feeling unsafe (kidding).
What part of this exactly is hanging you up? I think everyone would like to see evidence that you have gotten most of the work done yourself.
An aside, I am not going to be the one to help you anyway, because its been years since I programmed a PLC and it was for industrial work, not home security. Principles are the same, and ladder logic is universal, but I am not sure I can visualize the sequences you need.