I believe you simply drag the loop onto the ACID project from the explorer window..
Then you use the pencil tool to drag the actual loop signal where you want it to play.
Create a folder for your libraries on your hard-drive. Maybe call it Acid Loops.
Copy your libraries to that folder.
Open Acid or Vegas.
Make sure the Media Manager window is showing.
There's an icon that looks like books with an arrow next to it over the "explorer" section on the right. Clic on the arrow and select New Library.
Now you can name and chose where your library will be located.
After you've done that, hover your cursor over the icons next to the one you just used. There's one that loooks like a folder. That is the Add Files to the Media Library icon. Select that.
Next, you can select the folders you want to add to the Media Library. You'd probably select "Acid Loops". If you have other media in other locations, you can then add those after.
Now, whenever you want to search for, say, "Cymbal", you'll just type that into the Search window on the left side of Media Manager. Anything that has been tagged as having cymbal "characteristics" will show up.
HTH
Mario
Jay, I forgot to mention, in case you hadn't noticed, that the Help file for Media Manager is accessible via the question mark in the MM window.