How do I set up Firefox on new phone?

Go to play or apple store and install. Then login with the same mozilla account that you use on your computer. Make sure the sync options are checked on the computer. see screenshots of android and iphone

Thanks. The problem is in my PC and iPad.. The icon is there, the old emails show in the inbox, but can't send and receive email..

What are we talking about? Setting up sync or something about email?