I simply want to reset my Macbook Pro so I can sell it.

Boot into the Recovery Hard Drive:

OS X Lion includes a built in set of utilities in the Recovery HD. Restart your Mac and hold down the Command key and the R key (Command-R), and keep holding them until the Apple icon appears, indicating that your Mac is starting up. After the Recovery HD is finished starting up, you should see a desktop with a Mac OS X menu bar and a "Mac OS X Utilities" application window. Note: If you see a login window or your own desktop and icons, it is possible that you didn't hold Command-R early enough. Restart and try again.

In order to reinstall OS X Lion, you will need to be connected to an Ethernet or Wi-Fi network. The Wi-Fi menu item is in the upper-right corner of the screen. Click the icon to display all available Wi-Fi networks. Click your preferred network name and, if needed, enter a username and/or password.

Restoring iLife applications after Internet Restore of OS X Lion:

If you reinstall Lion on a new Mac that shipped with OS X Lion installed, on an erased or replaced hard drive, you can download iPhoto, iMovie, and GarageBand from the Mac App Store.

1. After installation, start from Lion.
2. Double-click the App Store icon in the dock.
3. Enter your Apple ID and password.
4. Click Purchases.
5. If you haven't previously accepted your bundled iLife applications within the Mac App Store, you should see your iLife applications appear in the Accept portion of the screen. Click Accept.
6. You may be asked for your Apple ID and password once again. Your iLife applications now move to the Purchased section. These applications are part of the software that came with your Lion based computer. Your account will not be charged for them. Click Install to compete installation of your applications.

Best,

Coander15

Did the Mac come with Lion when new, or did you upgrade?

How do I securely delete data from the machine?

We still don't know if the Mac had SL or L when new. If originally equipped with SL, whether reverting to it would make the computer more saleable.

How To Prepare a Mac For Sale

The OP has 10.7.3 Lion listed as their saved product. That may, or may be Mac they are trying to sell. We don't know that much yet.

What do you mean by I'm stuck?

If you have erased the Macintosh HD partition exit out, close, Disk Utility and then click on Reinstall Mac OS X and clcik Continue. Have the computer connected to your router with an Ethernet cable.

You will be asked which drive to install Lion to. Select the Macintosh HD partition and click next or OK and wait for Lion to download and start the install.

Once the install if finished and you are at the first screen, The Select Language screen, hold down the power button until the system turn off. It is now ready to be sold.