2

The first method is to click the option button, and then directly enter the label or directory.

three

The second method is to click the New Label button.

four

The third method is to select the title or text in the text, then right-click and add a bookmark.

five

According to the above three methods, after adding multiple bookmarks or directories, we can see that these bookmarks or directories are not graded. Now do multi-level directory operation.

six

Drag the lower bookmark or directory to the lower right of the upper directory, and a small triangle with a dotted line will appear. Put the catalog in this place and it's done.

Drag the secondary directory to the lower right of the primary directory, and drag the tertiary directory to the lower right of the secondary directory.

seven

According to this practice, the production of multi-level bookmarks or directories is completed in turn.