I've been working on the beginners course for about a month and find it helpful to write stuff out. I just tried to imagine a simple conversation I had with both my kids on a few occasions. I don't know if I got it right, though.
Kid says:
Quiero ir a la fiesta graduación.
I want to go to the graduation party.
And dad's reply is:
Lo siento pero no puede ir – fin de la conversación.
I’m sorry but you can’t go – end of the conversation.
When the point is pressed:
¿Por que?
Why?
Dad answers:
Porque no es su fiesta graduación y tiene que estudiar esta noche.
Because it’s not your graduation party and you have to study tonight.
Tell me if I did this right

Frank-Adam
September 26, 2007

Mauricio
October 9, 2007
Hello Frank,
That's very good. Here it is with proper grammar.. it's very close, well done.
Quiero ir a la fiesta de graduación
Lo siento pero no puedes ir - y esto es el fin de la conversación*. (*sounds a little funny in spanish. To get this point across we would say... "y punto!" (meaning you put a full stop on the conversation)
¿Por que?
Porque no es tu fiesta de graduación y tienes que estudiar esta noche.
So well done, I must say you are doing great for it to be your first month. I like the way you are thinking, mock up (real) conversations will get you a long way.
Regards
Mauricio.