Design software

I would like to know what software is out there for designing backgrounds like for a slide show. I've been doing a lot of iMovie projects using pictures and other's graphics but I'd like the freedom to design my own. I am very new to doing this type of thing so need lots of advice.

To give background for what I'm doing, I work in childrens ministry at my church and I create song video's for the kids basically with the song words added to pictures. But I'd like to go further and add my own backgrounds or a plethora of designs I could choose from along with possibly down the road adding some cartoon figures. Any ideas? I'm kinda lost.

There are a TON of options out there that will suit your needs. The main deciding factor is going to be your budget and how much you expect from the software.

At the very top of the line is Photoshop or Illustrator. Photoshop is, as the name implies, primarily for photo editing, but you can also do graphics and design in it. Illustrator is along the same lines, just more focused on illustrations (in case that wasn't apparent).

Down the price range from there, there are infinite options. There's Photoshop Elements, which is a pared down version of Photoshop at a much cheaper price.
A personal favorite of mine is Pixelmator. It comes in at $60, but it has much of the functionality of Photoshop.

You can also find a lot of free software out there if you look hard enough. Probably the most well-known is GIMP.

What specifically do you want to do? It would be easier to make specific recommendations if there was some frame of reference or example of what you do.

You could also always do everything by hand too actually. All you need is a scanner for the end result.

Corbab pretty much covered everything on the digital side of things though.