https://www.youtube.com/watch?v=pqr2bdxKC00&feature=youtube_gdata_player
You copy the modified apn list. Fron your sdcard to the /system/etc folder and overwrite the original.  You do this with root explorer or another file manger that had root access. Above is a quick video I made on how it's done. 
There is another way to do this , that let's you get to the hidden menu in settings that allows you to enter apn settings but for that you need a deodexed rom.
I will attach this file to this post tomorrow since I don't think I can do it from tapatalk.   I will still be making a thread on this and the other way as soon as I can. 
From my Galaxy Note 2 via Tapatalk