I want to improve myself.

I have learned studied English since I was a student. Now I am an English teacher. I think English is very beautiful. Actually, my major in my university is was Chinese language and literature. I taught Chinese in Thailand for one year after my graduation. Aand then I (unnecessary) came back to China to teach English. I have taught English for one year,. Bbut sometimes I feel puzzled about some English words and grammars. I want to improve myself.

 I Want to Improve Myself

I have been learning (learned) English since my student days. (I was a student.) Now I am an English teacher and (. I) think the language (English) is very beautiful. Actually, my major in (my) university was (is) Chinese language and literature. I taught Chinese in Thailand for one year after graduating (my graduation.) before returning (And then I came back) to China to teach English. I have now been teaching (taught) English for a (one) year (.) but still find (sometimes I feel puzzled about some) English words and grammar(s) puzzling at times. I want to improve myself.

Well written. I have suggested a few alternative phrases and word constructions to make your article read more naturally.