Go to View | Toolbars and check the Text Editor toolbar so it shows up. It has toolbar buttons to Toggle (create/delete) a bookmark on the current line Ctrl-B, T, as well as navigation to the next/prev bookmark, where the navigation is scoped to the solution, folder, or document, depending on which button you use.
Once you have a bookmark created, go to View | Other Windows and select the Bookmark Window (or just press Ctrl-W, B). That will display the list of all the bookmarks. You can double-click any bookmark to jump to it, or use the toolbar button in the Bookmark window for prev/next.
You can also name/rename your bookmarks in the Bookmark window. Right-click on the name and choose rename, or select the name and click it again to enter in to the edit mode.