where is the option key

On your Mac's keyboard. The one that says "Option" on it. Between Command and Control on the left side of the space bar, or between command and the arrow keys on the right side of the space bar.

If you are using a 3rd party external keyboard, its usually mapped to the "alt" key on Windows based keyboards.

Look in the support document you posted from. It states which charger and which charger cable goes with it based on the information in the Power section of the System report.

Otherwise, post your model / year of Mac and we can tell you what cable and power adapter you need.

For newer Macs,. it's going to be either a USB-C to USB-C cable or a USB-C to Magsafe 3 cable.

For older Macs and magsafe 1 and 2 and power adapters, the cable is built into the power adapter.