Reinstall OSX 10.6.3 did not format drive
I have purchased a copy of OS X 10.6.3, so that I can become the Administrator of the second hand Mac mini I purchased from ebay. I have now installed the new system software after backing up my files. However, the result was that my Mac is the same as before, not formatted, and I have an older operating system (10.6.3 as opposed to 10.6.8). How do I format the drive. I need to become the Administrator, that is why I bought the Snow Leopard software. Thankyou.
Mac mini, Mac OS X (10.6.8)