Previously I've almost always shot with fast primes lenses, where a shallow DOF could easily be achieved. Depth of field quite simply is the distance between the closest and farthest objects in an image that appear to be in focus.
Using a smaller aperture (higher f number) opens up more of an image to focus, whilst a larger aperture (smaller f number) closes down the image focus area. So if you want objects to really stand out in an image with a 'fuzzy' out of focus background, you choose a small f number. It's also worth noting that aperture size affects shutter speed and ISO rating, it's all part of the 'three pillars of photography' - more of that another time maybe!
The 18-55mm Fuji zoom lens runs from 18-55mm at f/2.8-f4.0. This offers the ability to produce good depth of field images with plenty of 'bokeh' (those out of focus areas).
Here's an image I shot at 45mm at f/4 which proves the out of focus area is nice, whilst offering a sharp, crisp in-focus area where it should be with the foreground and background helping to make the focussed area 'pop' out from the frame more.
With autumn well and truly upon us, I've applied a muted Lightroom preset I downloaded for free from here, which I think matches the current colours and shades of autumn really well.