(*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 CDN Rewrite plugin.
After you have installed the plugin, you will see a new item in the Settings menu - "CDN Rewrite". Hover your mouse over "Settings", and then click "CDN Rewrite":
You will see the settings for the plugin:
Next you should choose what file types should be served via UCDN, to do so enter the files' extensions in the field "File Extensions"
The next fields - CDN root URL for CSS and CDN root URL for JS are optional. If you have set different zones for .CSS and .JS you can set the urls.
Since you can enter file extensions in the fields, these options could be used if you have zones with big files (like multimedia):
After you are ready with the settings, click "Save Changes"
Now the files with the specified extensions will be served from UCDN.
Enter the CNAME you have created in the field "CDN Root URL". You can also enter the url for the zone like a14-10001.clients.ucdn.com