It's very easy to get started, you create an account (free) and then create your classes. If you teach/sponsor only one class/activity, you might only need to create one class. I created three just for practice, I also created one class for my Professional Development class so that I can demo the product. Once you've created the class, you get a unique log-in for each class. You can print out instructions for the log-in that look like this:
My students were able to send the text to sign up and got a response immediately. We then sent a few practice texts and even a poll! They loved it, actually asked me if I would start using it to remind them about tests, etc.
I can see it being very useful for large groups like band, choir, cheer, etc. The best thing about it is that no phone numbers are exchanged. You do have to set it up and send from a computer at the moment, the web site says they are working on an app that you could use from a smartphone.
The initial setup is free and you earn credits by signing up others. So, if you're interested, please sign up using my link!
Hope you enjoy this little APPle!