A welcome party is held for Tam from Vietnam at the share house where she's staying. Kaito has prepared a table full of good things to eat.
To say where you're from, use "[place] kara kimashita." "Kara" is a particle that indicates the starting point or place of origin. "Kimashita" is the past tense of the verb "kuru" or "to come." You can replace this with "desu" and say "Betonamu kara desu" or "I'm from Vietnam." Asking where someone is from: Say "Dochira kara desu ka" or "Where are you from?" "Dochira" is an interrogative meaning "where" that is more polite than "doko."
This is a response that acknowledges you understand what the person you're talking to has said. Be sure not to raise your intonation at the end of the sentence.