Introducing myself

My name is Masahiro Kaneda. I am 19 years old.

I'm from Miyazaki, and now I live in Okinawa.

I'm a college student.

I can't speak English.

I want to be able to speak English well.
And, I want to make a lot of friends.

Thank you for reading this note.

Good Job 

My name is Masahiro Kaneda. I'm a 19 year old college student.

Your age and the fact you are a college student are both about you. You can combine these facts and make the paragraph flow better.

I'm from Miyazaki, but I'm currently living in Okinawa.

-or-

I live in Okinawa, but I'm originally from Miyazaki.

The top makes the move to Okinawa seem temporary. If you are living in Okinawa while in college and plan on moving back to Miyazaki after you're done you can add 'for school', or 'while I attend college' if you want to be more formal, after Okinawa. The bottom makes the move to Okinawa sound permanent.

I can't speak English.

I want to be able to speak English well.

I also want to make a lot of friends.

-or-

I would also like to make a lot of friends.

You should not start sentences with conjunctions. They make your sentence sound very informal. Some would also argue it is not proper English. The use of the word 'want' may seem harsh and demanding. As you cannot demand someone be your friend the lower sentence is more polite.

Thank you for reading my introduction note.

Although it is often omitted in less formal writings you should state what you are thanking them for reading.