I would say: "Mon français n'est pas très bon," not "C'est pas bien".
I'm guessing you also tried to say "I taught myself by reading and writing by myself". Not only is that redundant, but it is awkward phrasing in French. I would say "J'ai appris..." but if you really want to emphasize that you did it yourself, you would say "je me SUIS appris"—this is the way to conjugate every French verb in the pronominal form: pronoun + me/te/lui/etc + Être (conjugated) + participe passé.
Also, it's la langue NORVEGIENNE (feminine).
Additionally, dommage is a masculine noun.
Hope this helps.