Hello Priscillia!
In Arabic, we use the vowel marks not for reading! it's for making some rules in Grammar related to "al-i3raab science" which the unique thing makes Arabic different from the other languages.
In English, how you do remember the words when you're speaking? == > I memorize them, it's the same thing you do for Arabic.
Al-i3raab takes attention to the variant of the marks in the final of word in Arabic. Example:
kitaabun / kitaabin / kitaaban ---- >كِتَابٌ كِتَابٍ كِتَابًا which are all of them : كتاب = a book. The one thing which is different on them is the final (-un / -in / -an ) Here al-i3raab educates the situation when we have to say with (un, in or an). :)
So, the most of the word change their final vowel marks. Or we sometimes make them with other vowels to have another meaning. (related to Grammar) example:
كَتَبَ = to write ( write in the past) kataba
كُتِبَ = to be written ( in the past) kutiba.
VOWEL MARKS USE FOR GRAMMAR NOT FOR THE PRONUNCIATION. I advice you as beginner to memorize the words as well. One day you'll notice the general way. Like in Maths, you start from 10+2 = 13 // 11+1 + 12 // 6+6=12... for the first time, then you generalize that by using x+y =12 for every x {0,1,...12} and y {0,1,...12}
Good luck