Myself

My name is Juan.  I'm a student of Biology and I'm learning English.  I'm a vegetarian.  I would like to visit England one day. I love the English music.  I think that I'm good at speaking, but when I'm writing I'm so bad, I guess.  Also, the pronunciation is full of mistakes.  I've been learning English with a great friend from U.K and it's a huge help.  But, I suppose that I need more.  I really enjoy learning English and teaching Spanish to someone.  If I've made mistakes, please correct them.  I wish you success with your leanring.   :D Thanks

(One big thing is that you need to put periods at the end of sentences, not commas!)  But, great try  :) and you are not as bad as you think!

Myself

My name is Juan, I'm Biology student of Biology, and I'm learning English. I'm a vegetarian, I would like to visit England one day, I love the english music. I think that I'm good at speaking English but when I'm writing I'm so bad I guess, but I think I'm bad at writing, and also the my pronunciation is full of mistakes, as well. I've been learning english with a great friend from the U.k, and it's been very helpful a huge help, but I suppose that I need more help. I really enjoy learning english, and teaching Spanish to someone, so If I'm mistaken, please correct it me, and the best of luck/I hope you succeed Succes (success is written wjth two 's' by the way) with your learning :D Thanks

Espero que te he ayudado y gracias para tu ayuda (:

Myself About me

My name is Juan, I'm a Biology student of Biology, and I'm learning English and I'm vegetarian. I would like to visit England one day; I love the English music. I think that I'm good speaking but when it comes to writing I'm not so good I guess, and also my pronunciation is full of mistakes. I've been learning English with a great friend from the UK, and it's a huge help, but I suppose (imagine?) that I need more. I really enjoy learning English, and teaching Spanish to others, so if I've made any mistakes, please correct them, and I wish you success with your learning :D Thanks

Las correcciones en negrita son los más importantes.  Los otros son más o menos errores estilísticos, pero mis sugerencias lo hacen parecer como si hubiera escrito por un Inglés :)

Unos tres más cosas...

If I'm mistake – Si me equivoco (de un hecho...) (pero es gramáticamente correcto :) )

to make mistakes – cometer un error (gramático, moral etc.)

Despues de "I believe", "I think", "I suppose" etc., evita 'that'.  No es incorrecto pero no parece muy inglés.

"I'm a vegetarian" y "I'm vegetarian" son correctos ambas :) se puede ser un adjectivo o un sustantivo. 

Myself About me

My name is Juan, I'm student of Biology and I'm learning English. I'm vegetarian and I would like to visit England one day. I love the English music. I think that I'm good at speaking but when I'm writing I'm so bad I guess, and also the my pronunciation is full of mistakes. I've been learning English with a great friend from the U.K. and it's been a huge help, but I suppose that I need more. I really enjoy learning English, and to teach Spanish to someone. so If I'm mistaken, please correct it me, and Success with your learning :D Thanks

Muy bien, tu amigo desde inglaterra!!

My name is Juan, I'm student of Biology, and I'm learning English. I'm vegetarian.I would like to visit England one day.I love english music.I think that I'm good at speaking but while writing,I'm so bad I guess and also the pronunciation is full of mistakes.I am learning english with a great friend from U.k and it's a huge help from him, but I think that I need more.I really enjoy learning english and teach Spanish to someone.So if I'm mistaken, please correct it and succeed with your learning :D Thanks