If you need further help, try to give us more details:
Are you using the 'default' version or is it one you got from these forums?
Are you able to play DayZ online?
From where did you get your games? (Steam, retail, BI, Amazon, etc)
Yikes. Well that's the near perfect storm of everything that could be wrong.
Before you even start to install our single player mods, you need to be sure of several things.
1. Install ArmA 2 and Operation Arrowhead
2. Run both ArmA 2 and Operation Arrowhead (just to the main menu and quit)
3. Fully update ArmA 2 and Operation Arrowhead
4. Install the beta patch
The Steam version is fully updated already, so you only need to run the games and install the beta patch. With the retail version, you are definitely not up to date and you need to install at least two updates, one of them pretty large.