[Solved]-Highcharts zones feature for imported text file-Highcharts

You can add zones by plot-options, for example:

    plotOptions: {
        series: {
            zones: [{
                value: 20,
                color: '#7cb5ec'
            }, {
                color: '#90ed7d'
            }],
            ...
        }
    }

Live demo: https://jsfiddle.net/BlackLabel/5w9rvonz/

API Reference: https://api.highcharts.com/highcharts/plotOptions.series.zones