To share a document, you must first attach it to a message in a sphere.
In the sphere, click on the icons in the "Write a message" field to discover everything that you can attach to your messages: documents, events, surveys, tags, ads, tasks,...
To attach a document or an image, click on the paperclip.
You will then have the choice to share GIFs, documents from your computer, or from OneDrive and Google Drive.
Once the documents are attached, share your message to publish them.
A message can include as many documents as you like.
Each document can be up to 20Mo (Standard account) and 150Mo (Premium account).