"We are writing."
Yes, there is only one present tense in Norwegian, so it covers both the simple present and the present continuous in English.
How does one differentiate between continuous action and present action in Norwegian?
Most of the time you will either know by context, or have no need to differentiate.
There are ways to express continuous action in Norwegian as well, which you'll learn in the 'Continuous' skill, but it's done much more sparingly than in English.
Er is left out because it's attached at the end of the word skriver? Am I right or wrong? D:
Still pretty good English for a person who speaks Portuguese as their native language. And neat of him to be taking Norwegian even though it isn't offered in Portuguese (only en, es, fr, de, it and eo are).