My MacBook Pro with OS X 10.7.5 created a Panic Report

What does it mean and what should I do? This happened after it finally turned back on after shutting down for some unknown reason (it was fully charged). It took several attempts at holding down the boot-up button for varying lengths of time. Once it came on I began searching the Apple Support options. I was afraid to use the Hardware Test recommended because it said I had to disconnect everything and I am backing up now to my Time Machine before doing anything else. I tried making an appointment at my local Genius Bar, but the Apple.com website makes finding a link to do so impossible. I'm in my 70s now. It's no longer the Apple Store of my 50s. (My first Apple was the Mac 512 around 1989.) I am new to this site. Thanks for any advice.