Sure m8
If you chose the default installation of the game, your AddOns folder should be located here :
C: / Codemasters / OperationFlashpoint / AddOns
This means that when you open the folder named "Codemasters" and then the "OperationFlash..." (OFP) -folder,
then you will see all kinds of crap inside the OFP folder, and all ya need to do is open the folder at
the top of the folder window, thats the one called "AddOns".
But maybe you have the european version 1.00
from summer 2001
It could be that there is no "AddOns" folder at all in the oldest version.
If so, download a few patches from the official game site, then you'll get the addons folder
After that, just put all addons into that folder.
PS. An OFP addon has to be an unzipped ".pbo" file, so if the addon was called :
"ST_Jeep"
Then you should put the "ST_Jeep.pbo" file into your AddOns folder
;D
Hope it works m8