Endnote provide excellent guides, short videos and live/recorded training on their official site:
EndNote 20 is available to all students and staff.
EndNote Online which is a more basic version of EndNote and is also available to all students and staff. For more information on EndNote Online please see here: https://clarivate.libguides.com/endnote_training/endnote_online
There are 100's of different referencing styles or output styles available through EndNote. The 500 most popular styles are available on the software and any additional styles needed can be downloaded from Output Styles on the Endnote website.
The file below is an EndNote style file for Harvard which follows the referencing guidelines on Harvard Referencing - SETU Waterford Libraries guide. It can be downloaded to EndNote Desktop by selecting it and then clicking the .ens link in your downloads folder. This will open up EndNote 20 where you will be prompted to save the style.