i have macbook 2008 late and like to upgrade to loin

You didn't say what operating system you have today. If it's OS X 10.5, you'll need to upgrade to OS X 10.6 first.

Assuming you have 1GB or more of memory, you would buy and install OS X 10.6. It's available from the online Apple store, in the US by calling 800-MY-APPLE, or online here. After OS X 10.6 installation, run Software Update until there are no more updates available, at which point you'll be at OS X 10.6.8.

If your goal is to install iTunes 10.7 or 11.0, you'll be able to do that at OS X 10.6.8.

If you want to install OS X 10.7 Lion, again call the online Apple store and purchase it. They will email you a code to download it from the App store. Note it requires 2GB of memory, with 4GB recommended.

If your MacBook is late 2008 aluminum or 2009 or newer, you can go to the App store to install the current OS X 10.8 Mountain Lion. Note it requires 2GB of memory, with 4GB recommended. You can go directly from OS X 10.6.8 to OS X 10.8 Mountain Lion, you do not need to install OS X 10.7 Lion as an intermediate step.

Lion is still available from Apple. You will have to call Apple Customer Care 1-800-692-7753 or 1-800-676-2775. to purchase it. Then within 3 days you will get an email with a code which you can use to download Lion from the App Store. The price is $19.99.

Is your MacBook is a late 2008 aluminum or 2009 or newer model? If not, you can't download and install OS X 10.8 Mountain Lion.