Hi deltran,
FYI, "Nanocomposite_Armour" is the green armor you are probably referring to. It is already a working model be it in the stable 2.2 version, or the current 2.3-development stage models.
There is however 4 pre-requisites to be met before this armor actually protects your soldiers.
1) You will need to kill an alien and recover a piece of "
Alien Armor"
That i believed u have already.
2) This allows for research into the armor which gives rise to a new research:
Nanocomposite ArmourThis you must research (which was not clear in your post). To research, you will need enough laboratory labs space, and have recruited scientists for the job. The more, the faster it will be done.
3) Next, you will actually need to produce the Nanocomposite Armour. This is done by queuing it in the workshop, and with valid recruited workers. Of course u can take forever (abt 1 month i think) for it to 'appear' in the market for purchase, but a better bet is to just manufacture them.
4) Last, you will have to equip the soldiers in the equipment screen (under aircraft menu).
There, hope this will increase your soldiers' survivability rate.