(*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 W3 Total Cache
After you have installed the plugin, you will see a new item in the Admin menu - "Performance". Hover your mouse over the text, and then click "General settings"
On the General Settings page, click the link "CDN" or scroll down to the settings. Tick the box next to "CDN:" to enable the functionality, then select "Generic Mirror" from the drop down-list, and click "Save all settings" to save the configuration.
After that scroll down to "Configuration" and enter the CNAME record you have configured for your zone in the field "Replace site's hostname with". You can also set to always use SSL or only HTTP from "SSL support".
Note: You should use the default zone address like "10001-14.b.cdn13.com", if you have selected "Enabled" in "SSL support", and want to use UCDN's shared certificate.
Now the static files in your blog will be served from UCDN.