I just had my oil changed in Firestone, they did'nt reset the Mant'ce Req'red light.
Can I do it myself?

Yes, there should be instructions in your owner's manual

Turn your car on. Switch the tripmeter to tripmeter 1. Turn the car off. Now hold the tripmeter reset knob down and at the same time turn the ignition switch to on (not start). Continue holding the tripmeter reset button down for about 10 seconds and the light will go off. Now you can release the reset knob. If you have the XLE model with the digital dash, you will actually see a bar graph move from left to right as the reset procedure progresses.

Mike