Make sure first your mac is compatible:
- iMac (Mid 2007 or newer)
- MacBook (Late 2008 Aluminum, or Early 2009 or newer)
- MacBook Pro (Mid/Late 2007 or newer)
- Xserve (Early 2009)
- MacBook Air (Late 2008 or newer)
- Mac mini (Early 2009 or newer)
- Mac Pro (Early 2008 or newer)
If it is mentioned aboved then you must contact apple and acquire 10.6.x and upgrade to 10.6.8 and then you may use the app store to upgrade to 10.8.2.
As judged by your signature. Your MacBook will be compatible. Any Apple Store will be able to help you instead of paying for 2 different operating systems as was mentioned before. They should be able to help you install ML for the cost off the software (19.99$). Make sure you have a Genius Bar appointment in order help you. It wouldn't make sense to buy a copy of obsolete software just to upgrade.
I Hope this Helps.
The first step in Upgrading... is to Snow Leopard = OS X 10.6.x
It is Not available as a download... It is a Paid Upgrade.
Do this first...
Check that your Mac meets the System Requirements for Snow Leopard...
Snow Leopard Tech Specs
If so... Purchase a Snow Leopard Install Disc...
After the Successful Install, run Software Update to get the latest updates for Snow Leopard.
Be sure to make a Backup of your Current System Before Upgrading...