Comment s'appelle cette fille? in French is "What's the name of that girl?" in English.
"How?" in English is Comment? in French.
Et toi, tu t'appelles comment? in French is "And you, what is your name?" in English.
"His name is what?" is an English equivalent of the French phrase Il s'appelle comment? The question translates literally as "He calls himself what?" or "He names himself what?" in English. The pronunciation will be "eel sa-pel kuh-maw" in French.
"How are you?" is an English equivalent of the French phrase Comment vas-tu? The pronunciation of the phrase in the present indicative of the second person informal singular -- which literally translates as "How are you going?" or "How do you go?" -- will be "kuh-maw va-tyoo" in French.
(il, elle) s'appelle ... means (he, she) is called ... in French.
Comment? in French is "How?" in English.
"How?" in English is Comment? in French.
"How are you?" in English is Comment allez-vous? in French.
Comment est-il? in French means "How is he/it?" in English.
Comment est votre...? in French means "How is your...?" in English.
Comment tu fais? in French means "How do you do it?" in English.
Je suis comment? in French means "How am I?" or "What do I look like?" in English.
Comment t'appelles-tu? in French means "What are you called?" or "What is your name?" in English.
"How do you spell it?" in English is Comment s'ecrit-il?in French.
Comment dit-on en français? in French is "How does one say in French?" in English.
Comment ça va? in French means "How are you?" in English.
"How was school?" in English means Comment était l'école?in French.