Creating an account with FrontlineCloud is free and easy.
First, go to https://cloud.frontlinesms.com
You will need an active email address that you can access to verify the email.
Once you submit the registration form, you will receive a confirmation email with a link to verify your account. You will need to click on that link and after that, you can access your account on Frontline!
To send or receive messages, you will need an Android phone or an account with an SMS aggregator service.
You can read more about that here: What do I need to get started in FrontlineCloud?