This is a problem for anyone attempting to make first steps in learning Spanish. How to distinguish when "ser" or "estar" must be used is simple.

First of all, use the verb "ser" when you want to talk about who you are, your profession, your nationality, where an event takes place, traits of someone's personality, dates and opinions.

Use the verb "estar" to talk about wherethings or people are located, temporary feelings or states or to construct the present continuous tense, as in "estoy corriendo" (I am running).

However, you must be aware that there are many exceptions or examples that do not fit exactly the definition because they are idiomatic expressions so the following tips will also be helpful:

-use "ser" when the verb is followed by a noun, so you say "es un coche" and not "esta un coche (it's a car).
-when and adjective follows the verb, as in "es blanco" or "es grande" (it's white or it's big).
-when the english adjective ens in -ing use "ser", when it ends in -ed (the past participle form) use "estar", as in "es interesante" or "estoy interesado" (it's interesting or I am interested).