opCharts HTML widgets is a way to define templates which opCharts can render and present to the user.
You will need system administration privileges so you can create the required files in the /usr/local/omk directory.
Inside /usr/local/omk/templates/public/ create a new template file and have its prefix .html.ep example: acme_list.html.ep
You can define any arbitrary HTML as you see fit, mojolicious templates are also supported, see more on rendering mojolicious templates at https://mojolicious.org/perldoc/Mojo/Template
After any change you will need to restart the omkd daemon
Now you have what content can be rendered you need a opCharts component to tell the dashboard it can render this new file.
inside /usr/local/omk/lib/json/opCharts/components.d/ create a new json file we will use acme_component.json
Name is what the component is called in the dashboards dropdown list
ep_template_file is the loccation of the template file.
titleText is the component display name