I am a Gabriela and I'm studying at "Escuela Politecnica Nacional". I need to learn English because it's necessary for my studies (or "major" in U.S.) and my profession. My university classes are very interesting but they're very hard. Today, I had a very difficult day because I worked with my mom in her restaurant, where I work as a waiter and cashier, which is very tiring. In the morning I'm taking English lessons but I don't understand my teacher very well and I really want to learn.

Good job, Gabriela, I believe I understood most of what you wrote. Note that in English, "career" is almost synonymous with "profession," and does not mean "studies." In U.S. English, we use the term "major" to refer to the main subject that you're studying at the university. Btw, in the U.S., we usually use the word "college" instead of "university," except in the official name or in more formal contexts, where there is a small difference in meaning.

In the last sentence, I changed "well" to "really" just to avoid repetition. Note that the word "well" usually comes at the end of the phrase, not before the complements.

In the next to last (or "penultimate") sentence, you made an excellent attempt to use consecutive relative clauses although you haven't studied advanced grammar yet.

Keep up the good work!

Presentation

I am a Gabriela and I study at "Escuela Politecnica Nacional". I need to learn English because I need it for my carrer career and my profession. My university is very interesting that is but also very hard. Today I had a very difficult day because I work with my mom in her restaurant. then I work how as a waiter and a cashier. This is very tired tiring.  In the morning, I take  of English lessons but I don't understand well to my teacher well and ;therefore, I want to learn well.

Presentation

I am a Gabriela and I study at "Escuela Politecnica Nacional". I need to learn English because I need it for my career and my profession. My university work is very interesting and very hard. today  I had a  very difficult day because I work with my mom in her restaurant then I work as a waitress and cashier; this is very tiring. In the morning I take English lessons  but I don't understand my teacher well  and I want to learn better.