The idea of a female monster is a popular fan theory and has been explored in some adaptations, but it is not part of Mary Shelley's original novel "Frankenstein."
In the novel, Victor is horrified by the consequences of his first creation and decides to abandon the idea of creating more life. He specifically states that he will not create a female companion for the monster, fearing the consequences of their potential offspring.
Therefore, there is no specific location in the novel where Victor went to make a female monster.