So as most Arma fans know you now need to put your arma 2 co on Steam. Thing is I don't know where to find and put the cd key so i can update and start playing dayz. Plz Help

Not sure if this is what you need, but in your Library go to the ArmA II CO game page, and scroll down a bit. On mine I'm seeing an enormously long serial number.

I actully found the solution. In the Serial key there is a small gap between. for example

xxxxx-xxxxxxxxx-xxxxxx[ ] xxxx-xxxx-xxxxxxxx[ ] x12121-x23232-x3434343-2323232-232323-2323

[] = gaps

You copy until the gap and put it on steam and then you copy the second one until the gap and put it on steam key. Should Work

Yes, its hidden in that big long number

When I put the two serial keys listed under my account into steam, it tells me some other account had already used these keys. Are not the keys given to us by GOG unique? What should I do in this case?