I have to write an essay referring to Michel Foucault's "The Subject and Power" and structuralism applied to Jane Austen's Pride and Prejudice. It is a sort of a literary analysis, using examples from the book and applying the theory of Structuralism. Anyone have any ideas, and/or examples in the book, with page numbers? Thanks!

First, as page numbers vary from edition to edition, and you do not specify which edition you are reading, an educator cannot give page numbers for the edition which you are assigned, but we can describe the episode in which a textual evidence is embedded. 
The nature of the essay you have been assigned to write is what is called a "theory/application" essay, in which you are asked to interpret a literary work in light of a specific theory. The point of this type of essay is for the instructor to see how well you have grasped both the theory and the text in a single assignment; applying a theory to a specific work requires you to understand the theory rather than just paraphrasing a summary of it.
There is a fairly standard way to approach this type of essay. The outline below should give you some idea of how to work through the essay.
1. Introduction: Foucault's analysis of power provides an interesting lens on Jane Austen because it allows readers to focus on the mechanisms of social control and power operating as the background to the novel. A structuralist reading foregrounds these implicit assumptions and relationships. You should then add a transition sentence talking about what elements of power you will discuss in the novel.
2. Binary Oppositions: A structuralist analysis reveals that the power structures in the novel are embedded in a series of binary oppositions. One of the most important is gentry/non-gentry. Others include rich/poor, male/female, parent/child, officer/subordinate, older/younger, attractive/unattractive. In each of these cases, the first of the paired qualities are associated with power and are more highly valued in the village. 
3. Control Mechanisms: For Foucault, informal control mechanisms function to enforce power structures. For example, village gossip and the way neighbors constantly watch each other and circulate information makes the village function almost as a panopticon. Note at the ball at Netherfield the way the villagers pay close attention to who dances with whom and how many times. It is also important to note that informal social control mechanisms are used to intimidate those who appear to be overstepping or challenging social norms, as when Lady Catherine tries to prevent Elizabeth from marrying Darcy. Foucault notes that we need to distinguish between violence and power. We can see that illustrated in the way that conformity is enforced by opinion rather than brute force. Lydia and Georgiana Darcy both face social ostracism, but their seductions by Wickham and rescues are not stories of rape or violence, but rather ones of seduction and persuasion and bribery. As you read through the book, you should look for examples of informal control mechanisms that regulate every aspect of behavior from food to dancing to clothing. 
4. Subversion: In many ways, Austen shows resistance to the operation of power in several moments of subversion. Her positive portraits of the Gardiners and the acceptance of them by Darcy and Elizabeth subverts the binary opposition between tradesmen and gentry, and suggests that noble character is not a matter of birth or profession but inner goodness. One can view Elizabeth's marriage to Darcy as ultimately an example of subversion or of assimilation.