Click the Commons icon in the global navigation bar (at the far left).
NOTE: This will take you away from your current screen, so I suggest right-clicking and choosing the "Open Link in New Tab" option.
On the Commons website, type your search parameters in the Search field. You can narrow the search by using the Type or Grade dropdown options.
Once you find something you're interested in, click to open it. There will be a description of the item. (The one issue I have with the Commons is you can't view the content of the item until you've uploaded it to a course shell. So you have to take a chance with things that someone else has created. You may end up deleting it if it's not what you really wanted.)
In the far right column, at the bottom is the License information. Some items are copyrighted but most are Creative Commons so they can be used.
Above that, in the right column, is the Import into Canvas section. Tick the box next to the course(s) you want to import the content into. Then click the Import into Course button. That's it!

The CVC-OEI Course Design Resources by CVC-OEI is licensed under a Creative Commons Attribution 4.0 International License Development of this course was funded by a grant from the California Community Colleges' Chancellor's Office.