[Solved]-how to enable drawing multiple lines on highstock basic-line graph?-Highcharts

Right now you have:

                    series : [{
                        name : 'Total Market',
                        data : arr,
                        tooltip: {
                            valueDecimals: 2
                        }
                    }]

So you have just one object inside series. If you want multiple series then should be something like that:

                    series : [{
                        name : 'Total Market I',
                        data : arr_1,
                        tooltip: {
                            valueDecimals: 2
                        }
                    },{
                        name : 'Total Market II',
                        data : arr_2,
                        tooltip: {
                            valueDecimals: 2
                        }
                    }]

Edit:

To add multiple series, push them to array:

var mySeries = [];

mySeries.push({
    name : 'Total Market I',
    data : arr_1
});
mySeries.push({
    name : 'Total Market II',
    data : arr_2
});
mySeries.push({
    name : 'Total Market III',
    data : arr_3
});

Then create chart:

series: mySeries