This is a correction of Chrisa's because hers looked pretty correct. I changed a few things that were necessary--like the dash between "English" and "speaking"--and some that are somewhat a matter of opinion, such as the placement of the commas in the last sentence. As far as changing "you"--it is extremely common in regular conversation to you use "you" when referring to "a person"; however, if it was a formal writing piece, "you" would very much be frowned upon. The title, "Because I want to know English" is a statement, not a question; therefore no question mark is necessary. But not knowing the writer's exact intent with it, you--"a person" lol--could play around with it quite a bit. Another acceptable form would be "Why I want to learn English" meaning "The reason I want to learn English".....On that note....proper titles are capitalized on the important words, so it'd be "The Reason I Want to Learn English", "Why I Want to Learn English", or "Why Do I Want to Learn English?".

Because Why do I want to know learn English?

OK, the reason why I want to learn English is because I like it. Also, there are some books that are not translated into Spanish, which I need to expand my knowledge. =) 
I like traveling and I think that by knowing English, you a person can then visit many English-speaking countries. And, And well, once you have learnt learned English, you can learn other languages. =)

Because I want to know English?

OK, the reason why I want to learn English is because I like it. Also, there are some books that are not translated into Spanish, which I need to expand my knowledge. =)
I like traveling and I think that by knowing English, you can visit many English speaking countries. And, well, once you have learnt English you can learn other languages. ​​=)

because I want to know English?

Ok, the reason I want to learn English is because I like it, plus you I have found books that are not translated into Spanish and are needed to expand my knowledge =) 
I like traveling and I think that by knowing English, you I could visit many English speaking countries, well, once you I learn English, I will have to learn other languages. ​​=)

Advice: don't say 'you' when you are talking about yourself.