Hola Kriss, let me make a stab at it... Mind you though coz I'm not a native...

Krisstina wrote:

Dear Madam or Sir,   I would like to put myself at your disposal for the position of Spanish language conversation(nal ?) assistant at education centres in your country. I wish to explain my motivation in a few words.   I am a 4th year Translation and Interpreting student at the University of Granada (Spain) and I am applying for this position that I view as a unique occasion for sharing my knowledge in Spanish language and culture, while at the same time ** seeking to complement my skills and experience ; my goal being to acquire the background necessary for my future as a professional translator and language teacher.   I believe this program as conversation assistant would provide me the ideal opportunity to contribute at your university and to improve my skills in English language and culture.   As I am seriously considering specializing in teaching languages after I      qualify as a translator, I am keenly interested in gaining more theoretical knowledge and practical skills in this area, especially in teaching Spanish as a foreign language ; so I would hope to be given the opportunity to work as language assistant abroad.   In addition to my university studies, my experience includes working part-time as a English and French teacher with children from Primary and Secondary school. So I believe that the combination of my little experience and my academic training is well-suited to the language assistant position you described.    United Kingdom is my first choice as a foreign country, both because fellow students have spoken very highly of language training there and because I visited UK (? Birmingham ?)  in summer 2001 and fell in love with the country. I am very eager to return whenever the opportunity arises.   I am seeking a career that will allow me to work with people in many different ways. I hope you'll give me this opportunity as much as I believe that I am qualified for the position you are trying to fill.   I have enclosed a copy of my qualifications and some information about me. Also I'm enclosing a reference ?letter? from Clara Inés ---------. Should you need any further information on my background and qualifications, please let me know.   With these words, I therefore wish to submit my candidature for your consideration, and I thank those who already have expressed their support. I am available for your comments and questions at any time.   Thank you very much for your time and for assessing my request. I am looking forward to your reply.   Yours faithfully,

I think you made very few grammatical mistakes. I felt I should change few words because you would sometimes use the same word twice (or the verb and the corresponding noun whithin the same sentence).
Definitely not as good as what you could get from a native but I sure did my best.

Buena suerte con tu applicacion (!?), chica (mon espagnol est très 'petit nègre').
Waïti.