HOW TO WORK WITH BOOKMARKS
For the convenience of usage, Book Designer considers separately the links related to bookmarks (bookmark links) and bookmark-independent links (outer links, such as http addresses, e-mail addresses, etc). If the loaded book contains some bookmarks, their names appear in the left window untitled as "bookmark name". If the book contains some outer links, they appear in the right window untitled as "bookmark link name". If some bookmark has links, they appear in the right window when you click on a bookmark.
Note. Book Designer can create automatically the chapter bookmarks during of new book formatting. If you want to activate this option, check "make chapter bookmarks" in "Settings" menu.
LEFT WINDOW BUTTONS
The left window of "Bookmarks" allows you to make certain operations with bookmarks.
to go to a bookmark, double click on its name.
add: allows you to add a new bookmark. In the main Book Designer window, select some word where you want to put a new bookmark and press add.
remove: remove the selected bookmark. To remove multiple bookmarks, first select them holding Ctrl key and then press remove.
clear all: remove all bookmarks and links (including the outer ones).
RIGHT WINDOW BUTTONS
   The right window of "Bookmarks"allows you to make certain operations with bookmark links and outer links. To see the links of a bookmark, click on its name in the left window. To see outer links, click on the red label (if it is visible) which is located near to the window top.
   A bookmark link appears in the book as an underlined word of blue color. If you click on this word being in the reader mode, Book Designer will navigate to the corresponding bookmark. Bookmark links can be assigned to the existed bookmarks only. To see if a bookmark has some links, click on its name in the left window.
   An outer link also appears as an underlined word of blue color, however the result of clicking on it depends on the link URL:
if it is http or ftp URL, you will be connected to the corresponding cite through Book Browser program;
if it is a file URL, the corresponding file will be loaded to Book Browser program;
if it is e-mail address URL, your mail server program will be run.
to go to a link, double click on its name.
add: allows you to add a new link to the chosen bookmark or a new outer link. 
To add a new bookmark link. Select some bookmark in the left window. In the main Book Designer window, select some word which you want to link to this bookmark. Press add and a new bookmark link will appear in the right window.
To add a new outer link. If the red label is visible, click on it. Select some word in the main Book Designer window. Press add. Type link URL in the box URL. Press done, and a new outer link will appear in the right window. If you do not want to add the new outer link, press cancel.
remove: remove the selected bookmark link or outer link.
To remove a bookmark link. Select the bookmark in the left window. Select the bookmark link in the right window. Press remove.
To remove an outer link. If the red label is visible, click on it. In the right window, select an outer link. Press remove.
clear all: remove all bookmark links belonging to the chosen bookmark or all the outer links.
To remove all the links of chosen bookmark. Select the bookmark in the left window and press clear all.
To remove all outer links. If the red label is visible, click on it. Press clear all.