Installation Leopard Will Not Open Up

I bought one installation disk for this new Leopard OS and it does not work. I open up the files, reset the whole thing so the installing can start up, and there when it starts I see the Mac logo with the spin, the blue screen, the white screen, and the grey screen all in the order I said they were. I hear my disk going crazy in there and I wait fifteen minutes to start and no, no window prompts of it. Could I please get help? Thank you.

 

Mac mini. One of the first if that makes a difference to you guys. Does it make a difference? I am curious about that.