Hello Javier~ you have a few mistakes in the text and hopefully you don't find it offensive that I took my liberties to point them out to you.

First notebook entry: Introducing myself

Hi! My name is Javier. I would like to improve (add to in front of the infinitive of the verb) my english (capital!) English because I know it could be better. I hope that somebody can/will help me.
I like music (electronic, dance, trip hop, rap...), reading (it's more like a noun here than verb because it's your hobby), talk (better say => discussions about politics or current (I don't know what this is), i (capital!) I like sports (swimming, (again you are talking about the sport not the verb to swim) football, basketball..) and i  I really like see movie watching movies.
I am 20 years old and i I am (no need to add am) study Law in Seville. And i I (don't be lazy - write capital I!) need to (mentioned this up there) improve my english English for my college but i I haven't got anybody to practice with.
I am happy, charismatic, simple and sincere, although I suppose that you should put the qualifiers.
Thanks for your attention.. See U you. (trust me - it's better to write formal than cut the words)

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I hope you found this helpful and that you will find a partner to talk to!~

First notebook entry: Introducing myself

Hi! My name is Javier. I would like improve my English because I think that it could be better. I hope that somebody will help me.
I like music (electronic, dance, trip hop, rap...), reading, talking about politics or current affairs, i like sports (swimming, football, basketball..) and I really like movies.
I am 20 years old and I am studying Law in Seville. And I need improve my English for my college but I haven't anybody to practise with.
I am happy, charismatic, simple and sincere, although I suppose that you should put the qualifiers.
Thanks for your attention.. See you.

Muy Bien!

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¡Hola! Mi nombre es Javier. Me gustaría mejorar mi Inglés, ya que podría ser mejor. Espero que alguien me ayude.
Me gusta la música (electrónica, dance, trip hop, rap ...), leer, hablar de política o actualidad, me gustan los deportes (natación, fútbol, baloncesto ..) y me gusta mucho ver películas.
Tengo 20 años y estoy estudiando Derecho en Sevilla. Y necesito mejorar mi Inglés para mi universidad, pero yo no tengo a nadie con quien practicar.
Soy alegre, carismático, sencillo y sincero, aunque supongo que usted será más apropiado para calificarme
Gracias por su atención . Saludos.