How do you know when to use a letter with an accent mark?
In English we do not use accent's over our letters. Some words in Spanish have accents over them. Is their a specific way to tell when a word needs an accent mark? Estoy confundido. Sé Necesito´.
4 Answers
The best way is to learn the accent when you learn the words, especially nouns and adjectives. As you study verb conjugations, you will need to memorize the endings and some of these have accents.
Accents are very important as they change the meanings of some words.
tú - you
tu - your
sí - yes
si - if
cómo - how
como - Can be like, as, or even I eat.
As you continue to study, it will make more sense and will become natural to you. You should practice writing the words with accents and using them in sentences. After a while, words will even look strange to you if they should have an accent and you heve left it off.
Keep studying and learning! 
This is very helpful. I've had a hard time trying to figure out if there is a "trick" of sorts to remembering the accents.
It's a matter of the word's spelling, so a big part of it is memorization. That's how you know the difference between sé (I know) and se (a multi-use pronoun).
But a lot of the time you will know that the word is pronounced differently than the usual pronunciation rules, with the stress on a syllable other than the usual. That's a time when you can always figure out that an accent is needed.
I would familiarize yourself with this reference article. It will help you to recognize why an accent mark in used on words when you know where the stress should fall.
