Trello

Trello is an app where you can create boards, lists, and cards, manage projects, organize tasks, and build team spirit. With Trello, teams can quickly set up and customize workflows for just about anything. Cards enable you can break down bigger tasks into steps with file attachment previews, reminders, checklists and comments – including emoji reactions. Trello allows you to integrate your top work tools, such as Dropbox, Google Drive, Confluence, Slack and Evernote.

You can find several tutorial videos here.