First, head to the Adobe Presets page. Then, make an Adobe account. You will then be able to download loads of interesting presets that have been shared by other artists.
Once you have downloaded the files, open up LIghtroom. In the develop module, go to your presets panel on the left hand side. Click on the plus(+) icon and select make new preset. You can now right click on the that new preset and select "Import". Locate the preset you downloaded from Adobe and import it. Now you can use it!