I just downloaded Open Office to my Mac Book Air and installed it. When I tried to open it a message came up saying it's developed by an unidentified source and my computer settings only allow installation of programs from Mac App Store or identified developers. I don't know anything about code. What can I do?
You have just seen GateKeeper in action.
If you are confident you downloaded a safe copy of the program, you can tell your Mac to "trust" that program and let it past the gate.
The linked article above goes into much detail on GateKeeper and I would scan it and review the steps above. If you find a lot of software you need triggers the warning, you could relax the settings, but I prefer to keep them at the defaults as I like to know when new code runs on my Mac.