The page provides the code. Your only homework mission: chase google for your preferred colors. How to Make a Call-to-Action Button — Support — WordPress.com
Do NOT overlook this gem
Sometimes we NEED a desktop to tame WordPress Admin. ChromeBooks satisfy.
WordPress.com has deprecated the “Press This” bookmarklet. Personal opinion: an intensely user-hostile decision.
A step-by-step guide, with screenies!
WordPress.com free + Premium users enjoy 3 options to show coming attractions, a/k/a an Editorial Calendar. Neither plug-in nor premium account is required. WP Business Tier, plus self-hosted folks, need a free plugin. Details follow.