On my D80, I always used the CCD clean mode in which the mirror lifts up to expose the sensor. Used blower. Worked most of the times. For stubborn dust, maybe you want to send it to Nikon service center. Some people in the external forum in below links have mentioned options. Be very careful and do it only if you are savy and comfortable.
I feel comfortable only with the blower method
Also caveat .. in the 2nd link .. scroll to the bottom of the page .. "If Canon, Nikon, Olympus, Pentax or Sigma, can tell that you have touched the low pass filter, your warranty is void." So better stick to blowing method.
do some reading up on the net, ts
searching clubsnap also works
a lot of people here clean their own sensor, me included
i think so far so good, no problem and very satisfied
but if you have no confidence to do it, suggest that you follow their advice and go to servicing centre lor
for me at first i never switch lens much, only have kit , not so much dust
after a while, keep switching,a lot of dust even when i observe proper procedure, i.e. switch in less windy area, turn off camera first, face down, do quickly
i think if i send for servicing everytime it gets too serious i die already, cannot buy anything