The O2 sensor plugs in.
The boot he refers to is the corrugated rubber intake hose that connects between the throttle body and the airflow sensor. These are known to crack with age letting unmetered air into the engine. This may be your only problem, a too lean mixture will set an O2 sensor code.
This attatches with two hose clamps, a monkey can change it in five minutes.
Look for the part at Autohausaz.com