What should i do about my macbook problem?

I've asked a question before about my MacBook. It's a late 2006 model and has the white screen with a flashing folder with a ? On it. So I did some extra research and found out that all I need to do is get pop in the install disc (snowleopard)

Now, my sister actually bought this laptop a few years ago off some dude on craigslist and when the screen went white she basically gave it to me and said if you can fix it you can have it and it was actually sitting at my dads house until a few months ago when I finally decided to get cracking on it. So anyway when she bought it, it didn't come with the disc.

Now, I've found free downloads for it on the Mac website yet everytime I put it on a disc and pop it into the laptop nothing happens. I figure I'm not using the right disc. I've been using a CD-R and the other day I was looking on amazon and the disc itself is actually a DVD-R disc. So as blonde as I sound is that the problem as to why its not working?

Or should I just stop being cheap and buy the installation disc?