In English we can turn a positive phrase into a negative one with the use of our word not.
He is here / He is not here.
The "not" itself is important, but it doesn't work alone. The sentence is made negative because the verb is made negative. In our example above the verb happens to be "is".
He is / He is not
Put the "not" anywhere else in the sentence and it won't make much sense. (Unless you're a fan of ridiculous irony... "He is here.... NOT!")
Understanding this makes it easier to understand how to form negatives in French. In order to turn a sentence negative, we need to make our verb negative. And to make a verb negative in French we simply wrap the verb in two little words: ne.... pas.
Play audio Ils viennent aujourd'hui = The come today
Play audio Ils ne viennent pas aujourd'hui = They do not come today
Play audio Il veut danser = He wants to dance
Play audio Il ne veut pas danser = He does not want to dance
Note that when the verb begins with a vowel, ne contracts into n' and it's added to the verb. For example:
Play audio Tu aimes les chats = You like cats
Play audio Tu n'aimes pas les chats = You do not like cats