Hi there,
There are tons of third party apple loop libraries available for purchase. Most commercial loop libraries today come in a variety of formats, including Apple Loop format. So, basically, any library that is available in Apple Loop format is instantly useable in Logic. Others can be too; but not as seamlessly and invisibly integrated as Apple Loop format libraries.
Yes, it is just a matter of copying them onto your hard drive. You can then bring them into your projects like you would any other audio file; in the File Browser, Audio Bin, Arrange Window,or drag and drop.
Optionally, you can also drag the folder containing the loops over your Apple Loops Browser if you want to have them available there for you. It's not essential to do this particular step to use them. But it is if you want them to appear in the Loop Browser.
The advantage of having them appear in the Loop Browser is that you can sort and filter your search results based on a variety of criteria. Me, personally I'm old fashioned and don't mind sorting and organizing them myself on my hard drive and bringing them in from there. But either way is fine.
So, depending what types of loop libraries you are looking for, look around on line - you'll find 'em! Here's a link to get you started:
http://www.smartloops.com/products/apple-loops.php
