NBDE is not too difficult to use. Probably easier to figure out than installing and learning a bend new DB system if you've already been using the built-in DB functions. But do what you like, obviously. If you want to try and stick with NBDE, once you import the NBDE package into your module, there are three main steps -
1. Place the NBDE Database container (placeable container) somewhere in the module that players cannot get to so they cannot open it.
2. Do a find across all the scripts in your module for the Get or SetCampaign functions. At the top of all those scripts, add the NBDE library by putting this at the top of the script:
#include "nbde_inc"
3. Finally, you replace all the regular Get/SetCampaign functions with the NBDE_ wrapper version of them. Or basically, just put NBDE_ in front of all those functions. For any of the SetCampaign functions, you will all need to place the FlushCampaignDatabase("DB_NAME") function after them at some point to physically save them from where they are temporarily store in that NBDE container to the actual database file.
As with everything, there are various things that might pop up or problems you might encounter. But if you read the instructions at the top of the nbde_inc, Kant did a very good job documenting the system and it should explain, in much more detail than this, the details of that system.