Go to Admin > Modules and enable the DXPR Builder module, the DXPR Builder Block Type and the DXPR Drag and Drop Node Type modules. This will make the DXPR Builder available for use, and create drag-and-drop block and node content types. (The modules have a number of dependencies which you should review and, if necessary, meet by downloading and installing the relevant modules from Drupal.org).
You will now be able to create drag-and-drop node and blocks.
To enable the builder on existing fields you have to set the field formatter to DXPR Builder. For example: on a node type with machine name page you can change the Formatter at admin/structure/types/manage/page/display.
If you don't use Bootstrap 3 in your theme:
Go to the DXPR Builder Settings Form at admin/config/content/dxpr_builder.