LibreOffice has extensive online help. In addition, a large community of users and developers support it. The following list shows some places where you can go for additional information.
https://help.libreoffice.org/
Extensive help on performing any task in LibreOffice.
https://www.libreoffice.org
Home page of LibreOffice
https://ask.libreoffice.org
Official question and answer page for LibreOffice.
http://www.taming-libreoffice.com/
Taming LibreOffice: books, news, tips and tricks.
http://www.pitonyak.org/oo.php
Extensive information about creating and using macros.
http://extensions.libreoffice.org/
Extension and template directory for LibreOffice.
https://www.worldlabel.com/Templates/openoffice-template.htm
Templates for creating labels with LibreOffice.