(*Disclaimer: Please be advised that the following instructions may have undergone some changes due to the third-party software and plugins updates.)
There are different plugins available for WordPress which can be useful if you plan to use a CDN for your blog. In this tutorial, we will be using WP Super Cache
After you have installed the plugin, you will see a new submenu in Settings - "WP Super Cache". Hover your mouse over "Settings", and then click "WP Super Cache"
On the WP Super Cache Settings page, select "Caching On" and click "Update Status".
Next click the tab "CDN". Enter your CNAME or zone address in the field "Off-site URL". You can also select the directories that will be served from UCDN, and exclude files based on regular expression.
Note: You should click "Skip https URLs to avoid mixed content errors" if you have not provided your own SSL certificate.
When you are ready with the settings, click "Save Changes"