A handful of phrases will carry you through your first day in Paris:

French	English	When
Bonjour !	Hello! / Good morning!	All day, to anyone — shops, neighbours, friends
Bonsoir !	Good evening!	From early evening onwards
Salut !	Hi! / Bye!	Only with friends and people your own age
Ça va ?	How are you? / All right?	After bonjour or salut, with people you know

The usual answer is Ça va bien, merci. — I'm fine, thanks. Then pass the question back: Et toi ? — And you? (To someone you'd address politely, it's Et vous ?)

To give your name, say Je m'appelle Marina. — My name is Marina (literally “I call myself Marina”). Meeting someone for the first time, say Enchanté ! — Nice to meet you! A woman writes it Enchantée; both sound exactly the same.