Can someone help me format this dialogue?

It looks fine to me.

One small quibble. (Isn't that always the case?)

The characters seem obvious without referring to them when they speak:

Pat~ said:

Her friend stopped by on his way to the palace, holding a great big flower. “Maria! You’re not going to the emperor with an empty pot, are you?said the friend. Couldn't you grow a great big flower like mine?"

Maria’s father, having overheard this, put his arm around Maria and consoled her. “It is up to you whether you go or not. said her father. You did your best, Maria, and your best is good enough to present to the emperor.”

Click to expand...

I agree with the fish. The additional attribution isn't wrong, but it isn't necessary. You might, maybe want to do away with the second "Maria" too.

eta: that would be the second "Maria" in dialogue, not the second use of the word "Maria."

eta again: Oh, hell. I keep getting it wrong. Let's try this:

Her friend stopped by on his way to the palace, holding a great big flower. “Maria! You’re not going to the emperor with an empty pot, are you?said the friend. Couldn't you grow a great big flower like mine?"

Maria’s father, having overheard this, put his arm around Maria her and consoled her. “It is up to you whether you go or not. said her father. You did your best, Maria, and your best is good enough to present to the emperor.”

Click to expand...

I'd lose the red stuff. And I hope I didn't screw it up this time. Harder to do in edit mode.

Silver King said:

One small quibble. (Isn't that always the case?)

The characters seem obvious without referring to them when they speak:

Click to expand...

I didn't suggest taking the tags out in case you'd wanted to keep a pause/beat there.

Otherwise, yes, you can safely take the tags out. It's clear who is speaking.

The official rule that I was taught years ago and that many still use is that when a new person starts talking, there should be a new paragraph. This is a rule that is rusting away though. I see lots of published books that don't follow it anymore. I'm afraid I don't have a style manual handy, but check in the Chicago Manual of Style or Strunk and White to see what they say. If your friend is writing for a particular publisher, he/she should find out which style manual they use. It's not something to obsess about though; it's easily fixed later on.

According to the "old" rule, the text should go like this:

Her friend stopped by on his way to the palace, holding a great big flower.

“Maria! You’re not going to the emperor with an empty pot, are you?” said the friend. “Couldn't you grow a great big flower like mine?"

Maria’s father, having overheard this, put his arm around Maria and consoled her.

“It is up to you whether you go or not,” said her father. “You did your best, Maria, and your best is good enough to present to the emperor.”