Yay, first question of the day.

The custom graphic CAN be saved as a PNG file... but it needs to be 256 colors, and ONLY 256 colors. I don't know about photoshop, but in MS Paint you do this by Save As then picking 256 color bitmap from the dropdown..

Edit:

I should say, that you'll probably lose some color when you convert. In my experience it's usually skin tones and the like, but it'll probably REALLY mess up the colors of your monster, unless it's a really simple one. My advice - edit using only 256 colors. After you save it as 256 colors, MS Paint puts you into a 256 color mode of sorts, where it won't let you mess up the 256 color-ness of the bitmap.

Facesets are pretty easy, they're ALWAYS 192x192 pixels large and each square is 42x42. Same 256 color limitation.

Battle charsets are a bit tougher - they're 144x384 overall, and each frame is 48x48, but don't forget that a row is considered one animation. If you want a character's animation to not.. animate, you have to put 3 of the same frame in a row, otherwise it'll blink.

As to where the templates are, I made this one a bit ago for the facesets. Right+Click/Save As..



The battle charset template is yet to be found, however. If I can't find it, I'll make one myself..

( All images are hosted using http://www.iownjoo.com )

Edit:

Another edit, dont' worry about being the only one to ask questions - a lot of people get their questions answered, then they leave forever. Hopefully you'll stick around and contribute to the forums! Of course, I should warn you about double posting - use edits instead of writing another post. You can post more than once in a thread, just don't reply to your own post, or the same post twice. Just a standard forum rule, heh. And why not, I'll throw in another picture..