You can made a simple present tense sentence negative by writing ne before the verb and pas after it (when ne is before a vowel, it becomes n’).
For example: Je ne veux pas y aller. / I don’t want to go there.
If you are writing a sentence using one of the following verbs + an infinitive, you don’t need to write pas: savoir, pouvoir, oser, and cesser.
For example: Je ne sais que faire. / I don’t know what to do.