Having a DSLR is fun but getting dust on the sensor is no fun. You would want to spot this before it shows up on your images. Here's how.
You need a big bright light source to point your Camera towards. You're probably looking at one right now, your Computer screen.
Easiest way to get the screen all white is either to change the Desktop background and remove all icons from the Desktop or you can configure your Browser to start with a blank screen and maximize it with a new Window.
Set your Camera to Aperture priority and select the smallest Aperture, 22 or something similar, and snap a picture of the white screen. Any dust will now show up on the image you captured.
Unless you can blow off the dust, leave the cleaning to professionals.