[Solved]-How to add background colors to category groupings in Highcharts-Highcharts

You can use the alternateGridColor option on xAxis:

"xAxis": {
    "categories": [
      "Category 1",
      "Category 2",
      "Category 3",
      "Category 4",
      "Category 5",
      "Category 6"
    ],
    "opposite": true,
     alternateGridColor: '#CCC'

If you look at the xAxis documentation there are quite a few different properties you can use.

Demo