I've seen this problem pop up a few times, so I thought I'd make a small
tut on how to import reources into RMXP. (just for all you noobs)
1. click the resource manager icon at the top of the screen
2. Click on the category of the file and then click "import"
3. When the resource pops up,
LEFT-click on the color you want invisible
and
RIGHT-click on the color you want to be "see-through".
4. Click "OK" and you're done!