You can post any file you have uploaded into Moodle directly onto a content block. The following video uses an image file as an example, but this process is the same for audio, video, or any other file you may wish to display on a content block.
Posting Image Files
Click the "Add a resource" dropdown menu and select "Link to a file or web site". This will bring up a page that lets you name and add alt text to your link. Then click "Choose or upload a link", which will take you to a list of the files you have uploaded to Moodle. Navigate to the file you want to link to and click the word "Choose" next to the file. Choose whether you want the image to open in the same window or a different window and then click "save and display". This will show you the file you chose. When you go back to the course page you will see a link to the file within the content block.