Well . Today we're going start to see  the structure of a sentence in english is very simple guys. You can make a sentence of the next way:

Simple present tense :

In  simple present you should use two auxiliary verbs do with the pronouns I, YOU,WE,THEY,YOU y does with HE, SHE, IT  in the negative form:

Example:

Affirmative form:

You do your homework all days of all weeks.

Negative Form:

You don't do your homework all days of all weeks.

Question Form:

Do you do your homework all days of all weeks?

Rules: in third person you add s or es on the verb but really this depends of the verb. If the verb ends with the vocal e you must add only the consonant s but if the verb ends in the consonant h you must add es.

In this link you can practice simple present tense: 
http://www.ego4u.com/en/cram-up/grammar/simple-
present/form/exercises


Auxiliary verb "do" in the simple present tense:
 You must the auxiliary verb "do" + not  when you are going to deny a sentence but if the sentence is in third person you must use "does" + not. but you shuuld know that you only can do or does in the negative sentence.


In the first link you can learn about auxiliary "do" in the simple present tense: 
http://www.youtube.com/watch?feature=endscreen&NR=1&v=X6uOjx_YxqU