How to organize your notes is highly personal. Begin to write every day. Review your notes on a regular basis.
You may want to create reference notes and will discover internal links right clicking on a note (link that you can paste in others).
Several methods exist, the most beginner friendly seems to be PARA (forte labs.com).
Create template is possible with Joplin, by using some plug-in (https://github.com/joplin/plug-in-templates).
Extremely important is to backup your notes. The backup plug-in is now integrated in standard, configure it as early as possible.
Write your first notes first on the desktop. Later you may want to come back to check the great synchronization features of Joplin that allow to get your notes on your phone or another computer.
Good luck!