There is a guide packaged inside! I can explain the details too:
1. Make a backup of your generator first.
2. Character packs are for the "RTP", or the assets that come with the game. You replace them in the TV folder for your specific game.
3. The Generator pack has folders are organized by male/female/child, and then a catalog of options for that section (use the face palette image to quickly find the one you want). TV means topview (the walksprite), and TVD is the downed sprite. Make sure you're in the correct section when replacing. In order to make the sprite change colour, it needs a colour mask image (filename with a _c at the end), so you're copying over two sprites.
4. Copy the sprite and its mask image into the TV/[category] folder. A kid sprite goes to the TV/Kid folder, for example. This replaces the image the generator uses. You have to do this every time you want a new character, unfortunately.
This process is the same for all Generator replacers and additions, including the SV (sideview) battlers.
If your game has sideview combat, I updated the Komyu-sho link. A highly recommended pairing for MV! (permissions are the same as this pack.) If you have MZ...I still recommend pasting the faces onto your MZ sprites!