Currently Being ModeratedDec 25, 2012 9:33 AM (in response to chetmate)
If your MBP meets these requirements:
You will need to purchase a Snow Leopard Disk from the online Apple store. Install it and the update the software. The result should be 10.6.8 version. Snow Leopard is a prerequisite for Lion.
Then you may purchase Lion from the app store and download it.
I suggest a minimum of 4 GB RAM in your MBP.