You don't "activate it". You either buy it in a store/internet or you could play a demo of it on your psp. (I bought it so I don't know how you get the demo.)
I cant believe I'm actually answering this question. flip on the power switch after you install and charge the battery. and for goodness sakes don't forget to put in a game.
Sometimes guns and supplies are locked. You must go to your Service Records and go to Medals. Go to the medals that are not obtained yet. Read the description and it tells you what you must do to...
There is only one way to do this. The last answer merely described a glitch in the online map Thin Ice. You will need custom firmware, cheatdevices, and many other hacking programs installed on you...