I am a new member of this forum. I am very courious about many aspect of English language and I really want to use it correctly. So, I'm going to ask you lots of questions! I hope you enjoy being kept busy with writing answers Emotion: wink
I'd like to ask you to correct every single error I make (if you are patient enough to do so, of course Emotion: wink).

This is my first question:
Are the articles in this sentence used correctly?
I threw a stone at a window yesterday. (I don't think of any particular window, just a window in general meaning).

Hi Julius, and welcome to the forums.

I didn't see any errors in your sentences.
The articles are used correctly.

Not quite for the reason you mean, though. If you threw the the stone, you do know which window you mean. You can't really not have a particular window in mind -- you threw the stone, so you did know the window. Your reader/listener, however, does not know which window you mean, so "a" is correct.
Thank you Barbara.