I found this out the hard way. First, in the page that you want to save and bookmark, instead of choosing (Add Bookmark), go up to the top of the page where the address is, click on it to activate it, and then right click and choose (copy) so that you can past it in when you get to your folder.
Then, in a new page, go up under (Bookmarks) and choose (Edit Bookmarks). This will give you a page with all your folders, and in the upper right corner, a place to enter search terms. In this you can put a general term that will be the theme of the folder you are looking for.
Say you are looking for the folder CARS, and in that folder you have a number of bookmarks that are on the subject of cars. As soon as you have finished typing CARS in the search box the page will change to all the bookmarks that have anything to do with the subject of cars. They will be in many folders, but what you want to look for in the middle column of information, which shows which folder they are in, is the group of bookmarks in the folder you are looking for, in this case CARS.
Now, and this is the key, pick one of the bookmarks listed under the folder cars, right click it and go down the drop down list and choose (Show in Folder). This will give you a new page with the folder CARS and below it all the bookmarks in it. You may have to scroll up to find the line with the folder if there are many bookmarks.
Now you can click on the line with the CARS folder, and go up under (Edit) and choose (Paste). You will have just found the folder you wanted and bookmarked your page.