From your question what I understand is that you need resources to develop a thematic study of Pride and Prejudice by Jane Austen.
Aside from the myriad of great resources we offer here on Enotes, I would also recommend that you visit the American Society of Jane Austen Scholars website which is included in the links with this answer.
As far as Pride and Prejudice goes, there has been extensive thematic research already published which will greatly help you expand your horizons when it comes to your main topic.
Now, keep in mind that Pride and Prejudice has a number of themes that can be explored, for which you will have to be very focused and specific as to what themes you are going to analyze. Is it the pride and the prejudice of the characters? Is it the institution of marriage in pre-Victorian times? The relationship among the Bennets? Jane and Bingley? The possibilities are endless.
Another big group, The Jane Austen Society of North America, also offers published papers which analyze thematically the different novels and that can also help you mold your research a bit better. That link is also included with this answer.
You will find that Pride and Prejudice is a much more complex read than many other contemporary works of its kind. There is a lot you can get from the story, the style, characters, plot, and even from the dialogue of the characters. Focus on one theme at a time and you will succeed.