Click the folder you want to move the item into. Click on 'OK'. Note that you cannot add a new link from this menu. Instead, go to the site you wish to bookmark, then click on 'Favorites', then 'Add to favorites'. Also, there is no way to keep bookmarks private.
Many organizations handle several functions.
For example, if you are a hospital with a nursing home attached, you might like to have a folder for long-term care links, and one for hospital links. If you have one or two links you use every day, you might find it useful to simply leave them outside your folders so that they are right there on the list when you click on 'Bookmarks'.