Arma 2 operation arrowhead combine help

[kingwael]

hi , i just got arma 2 and i want to combine it with my installed arma 2 operation arrowhead but i dont know how .
should i uninstall operation arrowhead first and then install arma 2 but then what
or can i install arma 2 with the exsisting operation arrowhead but still how can i combine .
i found some threads in he official page but they are very confussing and i asked they said that inorder to play on the servers here you must have combined operations
so plesae can someone help me :)
thanks in advance

[=VG= Outlanders]

You got retail Arma or Steam version?

[kingwael]

retail, why is there a diffrence between the two

[=VG= Outlanders]

Install Arma 2 and then Arma OA in same directory.
Then install last patch.