Spanish - How do you know which form of the verb ser to use in a sentence?

Question

kc_kennylau · Answer

Look at the pronoun?

kc_kennylau · Answer

I do not know if this is what you want to ask, but if the pronoun is "yo", use "soy", and etc.

kc_kennylau · Answer

Complete conjugation here: http://www.spanishdict.com/conjugate/ser

anonymous · Answer

I do know that, 
soy
 eres
 es
 somos
 sois
 son.   

I'm just getting confused when I have to decide which form to use in a sentence.

kc_kennylau · Answer

Look at the pronoun of the sentence
I: soy
You (singular+familiar): eres
He/She: es
You (singular+formal): es
We: somos
You (plural+familiar): sois
They: son
You (plural+formal): son