Young learners "parrot" at first and repetition is the key to learning. You might begin with a short "narrative." "Good morning. How am I? Today, I am fine, thank you. How are you? (you might get answers from some and then you will know who is listening, paying attention. Then you can ask individual students - a lot, if they aren't familiar with all this.
When you think they have it understood, you could even try "Stand up if you are fine." "Stand up if you are not fine."
Next, if there is still time, you can get pairs of students to ask each other. Keep it lively, keep it fun and they will pay attention. If you use any TPR (Total Physical Response), such as stand up, sit down, raise you hand, etc., you will know quickly whether or not they are following you.
If English is a foreign language for them, at first you need to repeat a lot, so they LISTEN, then get them to repeat so they SAY. If you think they can do those 2 things, you can write a word on the board, overhead, flash-card, etc. so they SEE it. Colored chalk, pens, etc. help to set the word in their "mind's eye."
Good luck and keep your eye on the clock!
Sra (aka Mme)