A great place to look for job openings in your field is through career Web sites. Google keywords such as "job search engines" and see what you get. Companies spend a lot of money and resources creating an online presence on various career Web sites so they can attract young talent who will be assets to the company. By searching for jobs in your fields of interest, you'll learn who the major competitors are in the field and who is hiring. Then, you will be able to research each company to see if one fits you better than another.
Some job search engine sites to get you started:
USA Jobs: The official job site of the U.S. Federal Government for students and recent graduates
Idealist.org: Nonprofit and international jobs