I am fond of helping Chinese learners.

I have just started meeting people in italki this week and my primary purpose is to improve my English. But I find that it is much more interesting in improving others' notebooks, and it becomes one of my enjoyable activities.
However, what makes me a little bit sad is that no correction is made for my notebook.

I hope that makes you a bit more happy =)
You are doing really well though! 

I love to help Chinese learners improve their Chinese by correcting their mistakes.

I have just started meeting people in italki this week and my primary purpose is to improve my English. But I find that it is much more interesting in improving others' notebooks and it becomes one of my favourite activities.
However, what makes me a little bit sad is that no correction is made for my notebook.

I am fond of helping Chinese learners

I have just started meeting people in italki this week and my primary purpose is to improve my English. However, I find that it is much more interesting to improve others' notebooks, and it has become one of my favorite parts.
However, it makes me a little bit sad is that no corrections are made for my notebook.

Good job, your english is really good :)