Another thing that you had asked is what happens if you don't do it right. Well, you didn't mention the engine model, but if it is an ABC, and you break it in too lean, you can do a lot of damage to the engine bore (the Chrome liner) and have an engine that will not give you many years of service. The reason to 'break in' an engine is to get a good coating of stuff (polymerized oil residue) built up into the liner which acts as a protective lubricating coating for years of service. Make sure you read and follow the directions in the manual about needle valve settings on the break-in procedure, or if you have questions post them here again.
Best of luck.
Curtis
P.S. It can be done alone, but be very careful and don't start if you are unsure of anything.