How to make some columns are fixed

Gantt
#1

how to make some columns are fixed

#2

Hello,
You can do that if you add several grids in the layout configuration:
https://docs.dhtmlx.com/gantt/desktop__layout_config.html
Here are examples:
http://snippet.dhtmlx.com/d6be1467a
http://snippet.dhtmlx.com/0e95aa933
http://snippet.dhtmlx.com/5/2c07e9730

Unfortunately, with that approach, inline editors won’t work in the second grid. The dev team will fix it in the future, but I cannot give you any ETA.

If you need something different, please, describe your question in more detail.