Sorry to hear that. Dust is unfortunately a fact of life for a DSLR user. It gets into the mirror box when we change lenses and it moves around when we zoom or focus our lenses, and some lenses are more prone to moving dust around than others.
There should be a clean sensor option in the user menu (with the box wrench icon) and you should be able to depress the shutter to open the shutter and flip up the mirror. From there, use a bulb type blower to blow the dust out. Giotto's rocket is a popular one, I use bulb blower I bought from Best Buy (Rocketfish) because I needed it NOW and no else carried the Giotto. Pointing the camera down give it a few good squeezes and you should be able to blow the dust out and away from the sensor. On my D700, shutting off the camera flips the mirror down.
Note: Make sure you have a fully charged battery and/or a AC adapter plugged in. It will not go in to sensor clean mode without a full charge. Also, don't point the tip too close the sensor, you don't want to touch it with the blower.
To see if you got all the dust out, mount a lens, focus on a white wall or clear blue sky, stop down to a small aperture (like f/22) and shoot. Upload the image and you should be able to tell how you did.
Don't let the dust stay on too long, you don't want it to build up, it will be harder to remove when you have to do a wet cleaning.
UNDER NO CIRCUMSTANCES SHOULD YOU USE COMPRESSED AIR TO REMOVE DUST. Products like Dust Off have a liquid propellant that can damage, stain or leave a residue on the anti-aliasing filter over the sensor. This may require additional wet cleaning or at worst, a trip to the shop for professional cleaning or replacement.