Loading Os X on empty harddrive....Lost Please help

Hello all first old HD was junk so installed a new 250 GB 5400 seagate hd which is completly empty. I lost my original boot disks that came with my comp and have spent all day trying to download torrents and install them on my empty mac. All im trying to acomplish is to instal Os X of some version on to my empty mac. I have downloaded numerous torrents and not sure what i need. I believe all i need is the .dmg file? Correct me if im wronge. I am trying to install this off of a flashdrive so im not sure if there is something i must do with my flash drive to make it bootable. When i turn my mac book on it goes to a screen of a folder with a questionmark in it flashing. When i hold option at boot i get a mouse but nothing tot click. Holding c at boot has no effect. HELP PLEASE1!!!!

Can't help you with "downloaded" software. Please read through this:
http://www.mac-forums.com/forums/os...49-what-os-disk-do-i-need-brief-overview.html

The only help you will get in downloading an operating system is the door slammed shut!

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