How to add 2 columns at blockmanager in grapesjs

Hello I am new in grapejs and using grapejs with angular6 i have seen Demo of grapesjs on []( https://grapesjs.com/demo.html). i want to create 2 columns at blockmanager as mentioned on below snapshot marked by red color i want to add 2 columns at blockmanager and when i drop that column on canvas then it should be appeared as above snapshot looks . i am using following code for doing same the code i copied from https://github.com/artf/grapesjs/wiki/Blocks and output of my code is on the below screen as you can see on above snapshot there is a component at right side of the screen in which 2...