One way to ask a question in English and Spanish, is to put an interrogative (question word) at the beginning of the sentence.

The interrogative words (question words):

• ¿Cómo?  How? or What?

• ¿Cuántos?  How?  or  How many?

• ¿De dónde?  Where?

• ¿Cuándo?  When?

• ¿Quién?  Who?

• ¿Quiénes?  Who (plural)?

• ¿Qué?  What (adjective)?

• ¿Cuál?  What (noun)?

Note that all Spanish question words have accents. 

Interrogative words can vary in meaning depending context.  When translating you must look for meaning.  It can not always be done "word for word."

To ask a sí or no question, you can reverse the order of the subject and verb by putting the verb before the subject. 
             STATEMENT:  Mario es bajo.
             QUESTION:  ¿Es bajo Mario?

You can also ask a question without changing the word order by raising the pitch of your voice at the end of the question. 
             STATEMENT:  Mario es bajo.
             QUESTION:  ¿Mario es bajo?

To answer a sí or no question, you would determine if you need to change the verb form.  If the question ask "tú (you)", you would need to answer "yo (I)." 
              QUESTION:  ¿Eres cómico?  Are you funny.
              ANSWER (positive):  Sí, soy cómico.   Yes, I am funny.
              ANSWER (negative):  No, no soy cómico.  No, I am not funny.
When answering a sí or no question, in the negative you need to use the word no twice in your answer.  The first time answers the question and is separated from the rest of the sentence by a comma.  The second no makes the sentence negative, which is the equivalent of the English word not.