How do I go into the game's files to read and change them? (They're .rez files)

enter image description here[Okay, so for this image on what I am asking for, there's an ability in the lower left corner of the image that is orange. The ability allows you to summon a Turret, but now since the game has changed, the ability is no longer there. What I need to know is how I can read .rez files in the game I play called Combat Arms Reloaded (the mode is Quarantine), and how can I change them in order to get this ability back? If anyone can help, I'd greatly appreciate it, and thank you for helping while giving the knowledge. Also, I'm really new to the website so I mess up, forgive me on that.]