"She reads the difficult newspapers."
Translation:Léann sí na nuachtáin dheacra.
Try using muscle memory: write in longhand on a sheet of paper twenty times “singular: an”. Turn the sheet over and write twenty times “plural: na”. Turn it over again, and in a second column write twenty more times “singular: an”. Turn it over once more, and in a second column write twenty more times “plural: na”. See if that helps you to get it.
You aren't missing out on any learning - all of the teaching content on Duolingo is available to all Duolingo users.
I'm not sure what you mean by "coping a thread". Assuming it's just a typo, you can copy the text from the website if you're using a larger screen with a mouse - selecting text and copying it seems to be disabled on smaller touch screens. Alternatively, you can copy the URL to link back to a discussion, but again, that's a function of the Web site - I don't know what your options are if you're using one of the various different phone/tablet apps to access Duolingo.