CD for new OS

You can take a look at the list of Apple Authorized Service Providers, and if there's one near you, you might be able to have them install Sierra for you. They are at https://locate.apple.com/

The jump from Lion to Sierra is almost seamless...there are a lot of great features on Sierra that will make you realize all the stuff that was missing from Lion all these years. Did you know Sierra has Siri in it? You can chat with the computer! It's not a radical user interface difference like Windows 10 was to earlier users. More of a interface that finally addresses all of the complaints you might have had about Mac up to now. I recommend it.

One thing you will want to look at is the amount of memory (RAM) on your computer. The requirements to run Sierra are only 2 gb, but you'll certainly want twice that or more to make the computer run at a reasonable speed.

Finally, it occurs to me that you might want to leave the computer with a trusted friend to download Sierra in town and pick it up later. Worth a thought.

Look at the third-party applications that you have in your Applications folder. Then visit roaringapps to see if they are compatible/available with macOS Sierra. These will likely need vendor updates. Anything that uses Java 6 will give you issues in Sierra. Also, anything that may have installed a device driver in Lion, will likely not work with macOS Sierra (printers, scanners, external drive software, 3G/4G telecom drivers, audio equipment, etc.) without a current vendor update for Sierra.

You will need at least 4GB of RAM, and 8 GB is better for macOS Sierra. Your early 2011 MBP can support up to 8GB officially by Apple, and upto 16 GB when using 2x8GB from Other World Computing. Many of us use memory from them, but receive no compensation for the endorsement. Check your machine specs. You might want to consider an internal storage upgrade to an SSD, as the original 500GB drive was SATA III quicksand.

Wondering if they made a CD to get new OS? (Sierra).

It will never happen.

I have Lion 10.7.5 When I bought this computer, they gave me the Lion CD.

It was never available on CD. It wouldn't fit on one either. It was, for a short time, available on a USB key.

I don't believe Best Buy will download an OS for you; however, you may be able to use their in-store Wifi to do it.

As for Siri: yes, you do talk to your computer/laptop. Siri is not a computer, she is an app. You can give her commands or dictate a letter or email with the Dictation feature.

There is no CD/DVD for Seirra other recent macOS versions.

You can likely go to an Apple store and get it downloaded on a USB flash drive.

Also, Sierra will likely not fit on a single sided DVD. The download is 4.77 GB