Log into your Drupal site.
In the Admin bar at the top, select Modules.
After you've downloaded the CDN Module from Drupal.org, select "Install new module" and upload the .zip.
Upload the CDN Module from your browser and install it.
Hopefully, everything will install successfully. That's something your hosting provider can help with.
Once the CDN Module has been successfully installed, go back to the Modules list and scroll down to CDN. Select Enable and Save Configuration.
Select Configure from the CDN Module
Change the status of the CDN Module to Enabled and Save configuration.
On the right hand side of the configuration screen, select the Details menu tab.
In Mode, select Origin Pull and enter the CNAME record generated when you created a CDN Resource. See How To Set Up A CDN Resource.
Scroll down and enable Far Future expiration. Save configuration.
Step 12 (optional)
On the right hand side of the CDN Module screen, select the Other tab.
Step 13 (optional)
Enable HTTPS for SSL support (optional). See how to Set Up SSL.
Your done. Test the configuration and run a Pingdom speed test.