Verb conjugation of "zwitschern" in German

I work as an actor in the theater. I have studied English for seven years, French and Spanish for two years. Well, my level of Spanish is too low to have a good conversation, but I understand it.
My correction were added and highlighted with yellow markers and attached to this email. Tell me now if you have any questions about grammar rules, since I was a teacher 10 years ago.
How long have you been practicing Spanish using this site and in which lesson are you now? I am now at vocabulary lesson number 3. It is still hard for me, but I'm quite new here and need to get better.