I'm using various .png files I got online, mostly ones created for Hoenn and GBA-style Kanto and Johto maps; a lot of them came from this forum. As for what I'm trying to do with it, I'm just trying to create maps for the new region I created for a fanfic project I'm working on. All of the tile map editors I've tried using either have a tile limit so low, it's impossible for me to do anything with them, or they require the tilemaps to be of a ridiculous extension, like .xtv or something else I can't reproduce. And most of them end up crashing on me for no reason while I'm using them; I was trying to make a worldmap on Tile Mapper, for example, and it froze up when I tried saving my progress for a second time, forcing me to shut it down and lose everything, and for some reason, it refuses to load the map file I DID manage to save.
I'm not doing anything drastic with them, I'm just using them in the way they were intended. I dunno why they're crashing on me, except maybe that they hate being used on Vista. I'd like to try and solve the problem I'm having with File Mapper, since I really like how you can grid the tilesets yourself and resize them any way you wish, meaning I don't have to worry about missized tilemaps, but any workable tilemapper would be fine.
Edit: Looking back at Tile Mapper, it looks like I can export my maps as .png files, like I wanted, so all I really need is someone with experience with the program that can help me fix its tendency to crash and not upload any of the map files it creates.