The U.C. Davis Library provides resources for many citations styles.
Luckily, there are many citation style guides available to help you avoid plagiarism and make proper citations. You will know what style guide to choose based on what your professor tells you.
The style guides you hear about most often are MLA, APA and Chicago, but the Sciences are more diverse in their style guides. Practically every field has its own style. Sometimes, even the journals have their own styles.