Your shutter speed should be on 1/50 or around that to achieve this result. This slows down your cameras lens when it is closing to capture the image, leaving time for the image to blur if there is motion.
When you lower your shutter speed, you may notice your exposure looks very bright so you will need to up your aperture and keep your ISO low so your images aren’t overexposed.
If it is a couple, you can have them sway, or dance. If it is a bride, she can twirl her dress. Anything that you can think of that involves movement, just keep motion in front of the camera. Capture the pics and fall in love with the blurry results!!