The Messages tab on your Mobile Text Alerts app allows you to view messages you have sent (as well as replies you have received back), and it allows you to send new messages:
Clicking on one of the message threads will show you a history of all messages sent to those recipients as well as replies they sent back. You can also send another message to that group of subscribers by typing something in and tapping the arrow button.
Sending a message
Click on the "+" icon toward the bottom right corner to start a new message:
From this page you can set up your message.
You'll first select who you want your message to be sent to; you can select either "all subscribers" or specific groups or individuals.
Next you'll select whether you want your message to be sent immediately or at a later time. If you select to send it later, it will ask you what date and time you would like to send it.
After you confirm the date and time, you can type out and send/schedule your message:
Inserting an attachment, name, or link
If you'd like, before sending your message you can click the paper clip icon and a screen like the following will pop up:
Selecting "Image" will allow you to select an image from your library or take a photo to attach to your message. This converts your message into an MMS, which also increases your maximum character count to 1550 instead of 160. (Note that each MMS counts as 3 messages per recipient instead of 1, and MMS will be sent to your subscribers through a different number than regular messages.)
Selecting the "Name" option will input your subscribers' individual names into your message (if you have their names stored in your Mobile Text Alerts database).
Selecting the "Link" option will allow you to shorten a link to make it more conducive to a text message and will also make the link trackable from your Reports->Link Tracking Report in your web control panel. (Most Facebook links sent using the "Link" option should also cause the link to open in the recipient's Facebook app rather than web browser.)