How to Setup a New Gmail Account on Your Samsung Galaxy S 4
Enter the username you want to use with Gmail and tap Done.
Enter the username you want. Hopefully you get this name on the first shot.
If your first choice isn't available, try again. There is no easy way to check before you do these steps. Eventually, you hit on an unused ID. When you are successful, it will congratulate you.nAccept the terms and conditions of the account.
You may want a lawyer to review this. Or not. Basically, the terms are that you should be nice and not try to cheat anyone. Don't abuse the privilege of having the account.