Girl : Hey, Tommy. Are you ready to plan the play for the school festival?
Boy : Totally, and...well... I was thinking about doing something with singing in it.
Girl : Singing?
Boy : Just hear me out. It would be a comedy about a school that uses singing to punish bad students.
Girl : They have to sing a songs?
Boy : No, not at all. They have to listen to someone sing a song in the most awful way.
Girl: Sounds pretty cool. How would the play go?
Boy : Well, we would have the initial scene in the classroom with all the students entering class.

Does have in bold have the same meaning as the sentence below:
event
if you have an event such as a meeting, party, or concert, it happens because you have organized it:
We're having a party on Saturday - you're very welcome to come.

This is from longman english dictionary online.

And could I say start instead of have?
like this:
Well, we would start the initial scene in the classroom with all the students entering class.

quote:

Well, we would start the initial scene in the classroom with all the students entering class.

Hello, Jay:

This sentence would be fine, but it means something a little different from 'have the scene....'

Start the scene means to begin the scene only. The scene would not take place entirely in the class.

Have the scene indicates that the entire scene would take place in the class.