A little patience. Maybe tomorrow when you can look at it fresh, try these couple things. First, check this page.
http://cownap.com/~mtmg/folderoptions.shtml
On windows XP it's under Tools on the menu, then folder options. That page was made when win 98 was out. But the thing is it'll still help to uncheck that checkbox beside "hide file extensions for known file types". That thing causes more problems than anything else. It really does. Then see if that helps. If not....
For the stock monster patrol, here are the gif file versions.
<img src="http://cownap.com/~mtmg/trucks/pics/Monster1.gif" width="256">
<img src="http://cownap.com/~mtmg/trucks/pics/Monster2.gif" width="256">
You can right click and save those, if you want. No act files to worry about.
If you want the blank ones (from the blank pack), send me an email and I will reply and send you the bmp version as an attachment.
Once you have them painted, then we'll work on putting it in the game for you. I know it seems like a lot to learn, and maybe even a bit too much at times, so let's just break it down into steps. There is no reason why you can't be doing the things you want to do. So, don't give up. It's only hard at the beginning. We'll get you there, if you really want it.