First notebook entry: Introducing myself

Hey! I am Douglas. I am from Brazil and I am doing a course in business administration. I want to live in Canada next year. Therefore, I must learn and master English as quickly as possible. I am counting on your help.

I thank God and you for this opportunity.
God bless you all.

You must use a capital letter always for I. It is not optional.

Contractions are used more in speech than in writing. The reader can decide whether or not they want to use a contraction. It is not wrong though to use I'm in writing but it is not necessary.

I do the course. Here you need the present continuous. I am doing a course or I am taking a course.

A course sounds better than the course in this context. - It is not the only course. It is one of many. So the indefinite article sounds better - well in English it does.

I want live. The second verb 'live' needs to be in the infinitive.   'to live'    What you have put sounds in English like:  Eu quero vive em vez de eu quero viver.

You do not need to make sentences longer than necessary by using 'and' to artificially link them together.

Bom dia.

First notebook entry: Introducing myself

Hey!! I'm Douglas and I'm from Brazil. I'm taking a course in business administration and I want live in Canada inext year..Therefore, I must learn and master English as quickly as possible! I count on you to help me!
I thank God and you, for this opportunity.
God bless you all.

(I live in Canada, It's really great here! ^_^)