So it is Farid, this character " ´ " called "Acento ortográfico" or "tilde" is proper to specifics words and this is depending of pronunciation, given this is not your case my recommendation is that you reads too much and you try learn it the most words possibles, this use have a pattern as next words: Canción, Prolongación, Conjugación, Contaminación etc. I mean, all words that finish with the "ión", and this mean the volume that you must give to this word.

Фарид, ВМЕСТО говорить нельзя. Ударения просто надо запомнить. Y nada más. Saludes desde Ucrania.

Also u and ú. Unfortunately, there is no short, simple answer. But if you know how to pronounce the word when speaking, here is how to know if a written accent is required when writing: http://users.ipfw.edu/jehle/courses/accents.htm