Turning a sentence negative simply involves a french grammatical change similar to the English "not". In French it is "ne....pas", however there are different versions of it. there is also "ne....rien" saying you want nothing "ne....jamais" meaning you want to "never" do something or "ne...plus" meaning you don't want to do something anymore. The way you form this in french is by putting the "ne" directly before the verb and the pronouns directly after. For example: "Je veux aller a la piscine" would turn to "je ne veux pas aller a la piscine" or "Je ne veux plus aller a la piscine".