Install cairo-dock-dnd2share-plug-in by entering the following commands in the terminal:
sudo apt update sudo apt install cairo-dock-dnd2share-plug-in
Dnd2share plug-in for Cairo-dock
A collection of official plug-ins and applets for cairo-dock. . This plug-in lets you share files easily. Drag-and-drop a file on the icon to upload it to one of the available hosting sites. This supports many sites, like DropBox, Imageshack, pastebin, etc. The user can upload text, image, video, and files.