'I am Chinese'  (this is correct apart from the capital letters)

 . . . 'but I am trying to improve my English'

 . . . 'please introduce yourself
or say what happened today'

teach me

i am from china ..although english is very difficult to learn but i am trying  to impove my english .
evebody..where are u from? how do u do? plese introduce yourself
or tell something about what happen today

teach me, please (polite)

I am a chinese ..english is very difficult, but I try to improve my english.
everybody..where are you from? how do you do (if I remember this correctly, the phrase is actually a greeting, like "hello".., "how are you?" as in "do you feel good?" is better)? please introduce yourself. or what happened today?

hope this will help, it's the best I can do..