Canvas Commons allows faculty members as well as TAs to share any specific Canvas object and even entire courses. If you would like to have a group created to share Canvas material with among faculty--either across an entire department or within specific areas--please submit a Support Center case to have the group created.
To share a specific item (such as Module, Page, or Assignment) you generally want to look for one of the setting icons (three vertical dots) you see throughout Canvas. For an assignment, for example, on the main Assignments landing page click the settings icon on the far right of the Assignment you wish to upload to Commons:
You will then land on a form-based page asking for information. All required fields will be marked with a red asterisk. A thumbnail image will also be required, though you can click the "Click to change" button and find a creative commons image on Flickr. Important: Files you attach to Assignments, Pages, Discussion prompts, etc., will NOT be included with them! You will have to share the file separately in Commons or type in an adequate description to describe the material. Also, videos recorded using the Panopto/Course Video menu must have their default permissions adjusted in order to
be shared on Commons, as will embedded Panopto videos on a Canvas page. Creators should submit a Support Center case if you wish to share a Panopto video with another user or otherwise make it public.
Additional, more detailed information along with screen captures is included in the attached PDF document. A complete guide to Commons is available from Canvas online, as well.
(If your department/program wishes to share MULTIPLE assignments that are to be used as common assignments for everyone teaching specific courses, you may want to instead consider Blueprint Courses. Blueprint courses "push out" material automatically from a master site, so that instructors need not have to import them one-by-one.)