You should use iFile since you're a beginner.
Now, for currency and other mods for simple games such as Unity-powered 3D games like the cheap hit game Occupation VR, all you need to do is edit a .plist file. These types of hacks are some of the easiest to do, which is also applied to some big name games like Real Racing 3.
All you have to do is navigate to the game files (this is the path for the game mentioned above as an example: /private/var/mobile/Applications/E6CF7014-462D-4D36-940E-AFF15BDE6E3F/Library/Preferences/com.the3daction.occp.plist). Your .plist file would be labeled similarly as the game's name, not the one labeled PeoplePicker.
Tap on that file, and it will list you options on how to open it. Tap on Property List Viewer, it'll be WAY easier for you to hack because you know what values are you changing.
I will post a tutorial of the hack later, so stay tuned.