Read and listen a lot! Find tons of interesting readings and videos to watch and listen to everyday that you can understand well. Since you don't know any English, you need to read and listen before you can write and speak well. Input before output! Good luck.

If you want to talk about the first song you'd say, "The first song is called _______." (Or if it already happened, "That song was called _______.") If you just want to say the name of any song that is currently playing, you'd say, "This song is called ___________."

Whoops, I put this as a comment. (see answer below).

"I was mad because of it" means you were angry. >:/ "I was sorry about it" means you did something wrong and had to apologize or say sorry. You might want to say "I was sad because of it" if it made you sad. :( or ;(

Karl is correct. You would say, "Lemons grow on the tree." This phrase is specific though. If you want to say where lemons grow generally, you would say: "Lemons grow on trees."

I'm a native English speaker from America. An English speaker would understand any of these which is what matters; however "exactly how we do it in Brazil," or "just like we do it in Brazil" sounds the most natural. It would sound a little unnatural to use "as." I would not use "like how." But again, any of these will be understood. Hope this helps.

Sorry I typed mine as a "comment." (see answer below).