Overheating is caused by the coolant not being circulated or cooled through the cooling system.
There are a couple things to check:
coolant leak or low coolant
radiator fan not working properly
You can check your coolant in the reservoir under the hood. Do not open the radiator cap at any time, because the system is under pressure. The reservoir is not and you should see a fill line for hot or cold. Make sure that you use the recommended coolant for your vehicle, which can be found in your owner's manual, and that it's a 50/50 mix of coolant and water.
The other items to be checked will probably have to be done at a certified shop or dealership. Good luck.
〉 Answered on Jul 27th, 2007 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines