How do I print text messages from iCloud

There is no option to print or view text messages from iCloud. Also see the following from Use Messages in iCloud - Apple Support

You can use Messages in iCloud on your iPhone, iPad, iPod touch, Apple Watch, and Mac. For your privacy, Messages in iCloud is end-to-end encrypted, which means you can't view or access Messages online via browser. 

The easiest way to print messages is by using an application on your computer such as PhoneView (Mac) or TouchCopy (Mac or Windows). Both will archive your messages to either pdf or text files which you can easily print or email.