The Announcements feature, unlike Chat, is a one-way communication tool that allows you to send messages directly to parent's devices. For two-way communication, refer to this article about using the Chat feature.
This article walks through how to make an announcement from the Teacher App; for a how-to on Announcements through the Administrator Dashboard, refer to this article.
How to make an announcement
On the Dashboard of the Teacher App, scroll to and tap on the "Announcements" tile. You'll be brought to the Announcements screen, where you'll see all the announcements your center has made that are relevant to you. To make a new announcement, tap on the plus-sign icon on the upper right of the screen to bring up the New Announcement screen.
On the New Announcement screen, tap on "Select a recipient" to open the pop-up options menu; then tap the group you would like to send a message to. If you tap "Specific class," a new field will appear on the New Announcement screen to let you choose which class you would like to send the message to, as well as whether it will go to that class's guardians, teachers, or both.
Enter a title (limited to 75 characters) and your message; tap into these fields to bring up your device's keyboard. When you're happy with your announcement, tap "Done" to send the announcement to its recipients and return to the Announcements screen.
You will now see your new announcement at the top of the screen. You may need to refresh the screen for it to appear. If you want to view its full message, tap on the announcement. When you're done viewing the message, tap the x on the upper left to return to the Announcements screen.