Hi,

For this you have to create a custom module or you can add it any of existing custom modules in your installation, its completely your choice. If you need to create as a new module, create a folder add necessary files like manifest file and init file, then add the folder static/src/js and continue as described in the above link .

In addition to the above, have a look at this too: https://www.odoo.yenthevg.com/creating-user-tour-odoo/

Thanks