Overworld map (WoB) tileset graphics location & assistance

I tried to PM Zeemis but his personal message quota is maxed out.

I'm in the middle of working on a secret hack but I've run in to a slight roadblock on something that Zeemis (or someone else here) might could help me with. I need to edit/replace some of the graphic tiles in the WoB tileset but do not know where to begin. Graphics editing is not my strongest suit in ROM hacking so I'm going to need a little guidance. I'm not looking to replace the whole graphic tileset just a few of the tiles. Do you know what the easiest method I can follow to replace the overworld tileset graphics? Or if someone would do the replacement(s) for me I would give them a solid credit line in the ending. I've got Nattak on board for music related items but the rest is being done by my solo so I'm a bit overworked with doing the rest. LOL Any help is greatly appreciated! :D