Collision Mask Problem

Hello, I am currently trying to adjust a collision mask for a sprite. I am trying to launch explorer to pull up the file and then use photoshop to adjust the masked area but I am stuck in explorer. When I click on the sprite in the animation panel and hit launch explorer I do not see the file for the sprite or the mask.

The sprite is a BMP file. Does it need to be PNG or another file type? Does anyone know why I cannot see the file or mask in explorer?

Thank you for any help you can give.

Edit: I have just tried with a PNG file and am having the same problem with it not showing up when I click launch explorer. The sprites I am using are stored in a folder on my desktop not in program files/scirra/images would that be the problem?

Try to make the file a tga file.And for png please keep the colors at 24bit or higher.

I tried but it's not working.

I just want to quickly mask off parts of sprites when I put them into game instead of making 2 sprites 1visible and 1 invisible masked one