what's the difference among join/ join in/ take part in?

A long way I joined a QQ group few days ago. The theme of the group is improving our oral English and making more friends of course. We are all Chinese, while we try our best to express ourselves in English. Our mother tongue is forbidden when we use our microphone to talk in the group. But the thing is, however, we cannot choose an appropriate topic to discuss. It just likes a class, a question raised, then came many feedbacks. Why? I throught we can chat freely in it. Just like friends talking to each other. Luckily, the thing changed a little with a new man's entering. He studies in Germany for his master's degree. His melodious accent and his fluent English impressed all of us. He guided us to talk about novel we read, soap opera we watched and our major, and our dreams. He is a new blood for this group. To be frank, I envy him so much. and I know, it would be a long way to go if I want to reach his level. What could I do?

A fresh start I quitted my first job as a secretary in a 5-star hotel because of many reasons. Left my familiar city to a new one. and then I found my present job in a short time. It's totally a new field to me. I have nothing working experience at this field before. Every day, I must learn new info in a fast spread. I am told to complete my tasks my boss gave me quickly. Otherwise, it would affect my partner's work process. I try my best to avoid it. But sometimes I still cannot meet the requirements for my less experience. I feel the working stress, but anyway, I won't give up. It's such a fresh start for me. I will try my best to make the situation better.