Documentation on the website is quite extensive and explains everything there is about the library, but just in short, this is how it goes:
Load chart.js script, you can download it locally or use CDN link. After that, insert the global chart configuration – this is the code which starts with…
And now you can choose the chart – all you need to do is add data structure for any of the charts:
The next step is to initiate the chart:
And then use HTML canvas element where the script will draw the chart:
And that’s all. Have a look at my CodePen example with a working chart. I used example from the website documentation, with only difference that I activated the responsive mode (you can find it in global settings).