Here are two good databases to get you started. There are more recommendations on the Biology Research Guide.
Many more tutorials gathered at the following sites:
Citation tools allow you to save and organize your research. They also let you create formatted bibliographies.
Downloadable as a standalone program from OIT, EndNote is a powerful citation tool for organizing your research and creating formatted citations. In addition to the standalone option, you can create an EndNote Web account.
Downloadable as a standalone program or a Firefox extension, Zotero is designed to store content in any format, including PDFs, images, audio and video files, and snapshots of web pages. Zotero operates with thousands of sites, and automatically indexes your library for ease of access.
Free PDF and reference manager. Read, annotate, organize, and collaborate on research projects with others using Mendeley.