Trying to unzip an image?

Ok so i'm trying to update my mac os 10.4 to mac os 10.5. I downloaded an image (because countless torrents weren't working). I used a program called betterzip to extract the files, but it didn't give me a dmg or iso file, it just gave me a folder with a bunch of things like this (vmdk vmem vmsn vram ......) but no dmg to put on a thumb drive and use to boot my computer. Can someone tell me what to do, or give me a good torrent to upgrade to 10.5 (not 10.6 because i'm running a PPC Mac). Help please!!!!