your mac will support 10.7.2 to current you will need to install to a new drive, a new partition of if you wish to use your entire internal HD you will need to either replace with a new drive or format out your current OS which will destroy all data
Backup your data then boot to the drive by restarting and holding down C with the disk inserted until the install process begins. If it fails for any reason you may also need to set the clock to a time where OS X 10.7 was public release. Or you may need to install with the disks that came with your computer as the 2011 precedes recovery, but should be OS X 10.7.2 or later depending on when it was purchased.
Do not proceed without a backup or without the original drive in a safe place (not in the computer ) if you insist on installing without a backup and you replace the drive.