Bookmark games in ChessBase
There is no separate bookmarking feature,but there is a way to do this.
At the point in the game where you want to insert your "bookmark", right-click on the move, select "Special annotation" from the popup menu, and select "Set medal" from the submenu.
Choose a medal type (I typically select "User") and click "OK".
Then be sure to use "Replace game" (File/Replace) to save your bookmark.
To find your game later, either look for the medal in the game list (if it's a small database) or use the "Medals" tab in the search mask to look for all games containing the type of medal you use for your bookmarks. When you double-click on the game to load it (after a search), the game will be loaded with that exact position already on the chessboard.
To "unbookmark" a game, just right-click on the move, select "Special annotation/Set medal", click on the proper medal box to remove it, and click "OK".