Dear Sir or Madam,
I am writing in reply to your advertisement in Gazeta Wyborcza for (na co aplikujesz).
As you can see from my enclosed CV, I finished my degree in .......(economics, law etc).
I am very interested in starting possible career in .......and feel very enthusiastic about it.
I should mention that I am available to attend an interview any time which might be convenient.
Please do not hesitate to contact me on my land line number (or cell phone) if you need any further information.
I look forward to hearing from you.
Yours sincerely,
........................