Thats pretty much it, although only aperture pysically adjusts the size of the hole in the lens. Shutter speed controls how long the shutter curtain opens to reveal the actual sensor to light, and the ISO amplifies the sensor's sensitivity to light.
To get an exposure, you need to adjust each of these, as they are all linked.
If you want a fast shutter speed, you need a big hole (wide aperture, lower f/number) to let more light in. However if you want as much in focus as possible, you need a narrow aperture (small hole, higher f/number) So as you cant have both, you'd adjust the ISO to make the sensor more sensitive to light, allowing the faster shutter speed. You can then close the aperture to get the required depth of field, or amount in focus.
Higher ISO means a comprimise of more digital noise in your photo.
To get the effect you want of blurred backgrounds, you need to lowest f/number you can, so on your lens will be between f/3.5 and f/5.6 depending on how much you are zoomed in.
Ideally you want a lens that can go lower, as this will give a much better effect, however by maximising the distance of the subject from the background, you can get a similar effect.
