This tutorial explains, how to create sliding sidebar and add content in this sliding sidebar as shown in the demo.
Enable Animated Sliding Sidebar
Navigate to: Administration > Appearance > Appearance settings > Kartpro
example.com/admin/appearance/settings/kartpro
Create a Block
You can create a new block or use existing blocks. You can create new block from:
Administration > Content > Block
example.com/admin/content/block
Assign Block to Sidebar Sliding
Navigate to: Home > Administration > Structure > Block layout
example.com/admin/structure/block
Place the block in Sidebar Sliding region.