You need to get a paint program (like photoshop) and create a transparent mask for some parts of the foreground so that the background will show thru. I had to learn to do it. It`s a little complicated at first unless you know your graphics stuff. But once done, you won`t forget.

This link might help.

http://www.wikihow.com/Add-a-Layer-Mask-in-Photoshop

I would definitely back Paint.net as the easiest tool to use for this job as well. But I'll be honest, I don't see much point in making transparency when it is just still images anyhoo.

I agree with everyone, I had not ever worked with any of the programs, but I down loaded but Paint.net and gimp. I agree that Paint.net is a lot simpler to work with, but gimp does so much more. I keep them both up and use them both to do different functions. As far as gimp, go to YouTube and watch a couple of videos taking you step by step through cutting out images, and before long you should be able to easily do what you want to.