Firstly, make sure you can set the shutter speed manually. If yes, set it either to 1/5 second or 1 second. The aperture value can remain large, f/1.8-f/2.8 in order to separate your subject from the background. Switch on your pop-up flash (if you don't own a flashgun) and there we go, take the photo.
I used exactly the same method to produce the following photos: