How do you use "in" or "into"?

How do you use "en" and "ett"? Thank you :)

How do you use "it", "this" or "that"? I always get confused when I'm writing a sentence using it(?).

First notebook entry: Introducing myself I'm here to improve my english, because I 'm not taking English classes, I'm just doing lessons on the internet. I hope italki helps me on this.