Bricks provides you with its own, built-in sidebar generator. Located in your WordPress dashboard under Bricks > Sidebars it lets you to create unlimited sidebars (widgetized areas).
All you need to do is give your sidebar a name and description (optional), and click Create new sidebar.
Once your custom sidebar is created go to Appearance > Widgets and drag and drop the widgets of your choice into your newly created sidebar.
You can now add this newly created sidebar inside the builder by dragging the Sidebar element onto the canvas.