On my 1999 Ford F350 the service engine soon light came on. Is there a simple way to find out want is wrong and how to turn off the light. How long can you drive with the light on Please help ASAP

Many auto parts stores will read codes for free; otherwise, buy an inexpensive code reader and attach it to the Data Link Connector under the dash. You really should find out what the code(s) is/are ASAP. It could indicate an engine or transmission problem.