I have written a paper in my own language. Is it right to write it in my CV as a published paper?
If you have published a paper, you should include it in your CV. It does not matter what language the paper is in.
For the aid of people who do not speak the language, however, you may wish to include a translation of the paper title as a note, e.g.,:
J. Caesar, Commentarii de Bello Gallico [Commentaries on the Gallic war], Caesar House Press, 49 BC, (in Latin)
Of course you should. It is well known that the best journals are in English but there are others that can be not bad and they are not necessarily written in English. In South America there are a couple of journals that are not on the top ten, but maybe on the second quartile and they have articles both in English and Spanish. Also, you worked on that paper so this may not add a lot to your cv but it is better than nothing! :)
You should, if you consider this work worth mentioning. Interestingly, this could trigger the curiosity of the reader, with if often nice when people receive hundredth of resumes.
If you "have had a 20 min talk about it", I guess it could be at a conference. It could be tagged for instance with "National conference" (if it was indeed national), and the title translated as suggested by @jakebeal. However, international conferences exist in other languages than English, so it could be an international conference, and you should mention that, to help the reader evaluate the context of publication.