If you want to use the online save editor there is basically a step by step guide at the bottom of the Walkthrough.
For the downloadable save editor:
- Start the game and make a save
- Download the save editor, then unzip it
- Start the application (RpgMakerSaveEdit)
- It should open a file browser, now you want to open the save file you want to edit, for this game the file path should be something like ("Where ever you keep your games"\Npri_alpha030_fixed2\Save). Then you should select the save file you would like to edit, which will be whatever save slot you saved in, i.e. if you saved your game in slot 3 then you want to select (Save003.rvdata2)
- Next the save editor should open up the save file and you should be able to edit things, the "Party" tab will have things like gold and stats for the Male Protagonist and the Priestess, you simply need to change the numbers you want to change, i.e. if you want more gold then click the number next to the word "Gold" and then replace it with however much you want
- If you want to give yourself more items then you can change to the "Items" tab in the top left and change the amount you have, be aware that all the item names are in Japanese and as far as I know there is no way to change them to English, you could try machine translating them with an app on your phone like google translate or by copying and pasting each name into a online translator in your browser, but the online save editor would be better for this since you can directly translate in the browser
- If you want to edit variables and/or switches then you need to go to the top left of the save editor and click the Advanced tab, then click "Edit Switches and Variables", Now there should be two more tabs just below where the advanced tab was in the upper left called "Switches" and "Variables", similarly to the "Items" tab these will be in Japanese, for the variables you can look at the bottom of the Walkthrough to see a list of translated variables, for the switches you will have to rely on machine translation again.
- After you are done go to the file tab in the top left and select "Save and Exit", your save file should now be updated and opening it up in game should show all your changes.
I tried to be pretty through here but let me know if something is still unclear or if I missed something, I don't use the downloadable save editor much so I probably don't know many tips or tricks for it.