Small Engines (Lawn Mowers, etc.): Banging upon start, briggs and stratton, stroke oil

Question
I started my Briggs and Stratton mower as usual.  This time it sounded like a plane engine, ready for take off.  White smoke emitted from under the mower and the banging sound began.  I was nervous that the mower would blow up so I shut it down.  Started it up again and let it run for a couple of minutes with the same symptoms.  I want to fix it myself, yet I do not know where to start. I did put new 2 stroke oil and fresh gas in 2 weeks ago and have not used it since.  I am a very mechanically inclined girl, but simple instructions would be great.  Thank you.

Answer
Check the blade bolt...sometimes they loosen just a little bit but make a heck of a racket.  While you're under the mower, check the engine mounting bolts as well.
I'd use a 1/2" drive ratchet on the blade bolt.  You may want to take the blade off and check the blade adapter.
Let me know what you find.
Eric