You can use the Rich Content Editor to insert course files from the Content Selector. The Rich Content Editor is used in features that support the editor (Announcements, Assignments, Discussions, Pages, Quizzes, or Syllabus).
Open Rich Content Editor
Open the Rich Content Editor using one of the Canvas features which support the Editor.
Create your content in the Rich Content Editor. The file will be automatically inserted wherever your cursor is in the Rich Content Editor. You can either insert a link directly , or you can highlight text where you want to create a direct link .
You have the option to link to existing course files  or upload a new file. Click the Upload a new file link  to add a new file to the course.
Upload New File
If you choose to upload a new file, select a folder for the file . Click the Choose File or Browse button .
Click the title of the file you want to insert . Click Open to upload the file .
Click the Upload button.
Note: If the size of your file exceeds your course storage quota, Canvas displays an upload error. Talk to your system administrator or choose a different file to upload.
View File Link
View your link in the Rich Content Editor. If you inserted the link where your cursor was located, the link displays as the file name . If you highlighted text for the link, the link is associated with the text .
Click the Save button.
Note: When using the Rich Content Editor in Assignments, Discussions, Pages, and Quizzes, you have the option to Save & Publish. When using the Rich Content Editor in the Syllabus and Discussions pages, the Save button may appear as “Update Syllabus” or “Post Reply”.
View your file.
If your document is supported by the document previewer, you can preview the file by clicking the Preview icon.