Failing to cite the sources from which you obtained information constitutes plagiarism, which comes with serious academic consequences. Make sure you have all the information you need to cite a source, even if you're not 100% sure you'll use the source in your final paper or project.
Check with your professor to find out if s/he wants you to follow specific style guidelines when writing your paper. There are several types of manuals or style guides for writing research papers. Two common styles are MLA (Modern Language Association) and APA (American Psychological Association). As you format your paper and citations, you may want to consult one of the following resources: