PubMed has officially implemented its new interface. This is a change that has been in the works for a while; an FAQ about the transition is available and may answer many questions you have. The National Library of Medicine has also created some helpful quick tours and other documentation to help you learn to navigate the new interface. Don't hesitate to reach out to me with questions.
If you're looking for journal articles on a particular topic, this is the place to start. Literature databases, or indexes, track the individual articles published in the thousands of research journals available in biology. Some indexes are built for very particular fields of study, while others are broad (but less comprehensive).
When you find an article of interest in an index, click the "Find It" button by that entry to get to the full text. If we have a subscription, "Find It" will provide a link to the journal article. (Or if we have the print, it will provide a link to the catalog with the location and call number.)
(A few databases, like Academic Search Complete, include full text for some articles. These databases may allow you to search only for articles available in full text, but be aware that you are only searching a small portion of the articles we actually subscribe to.)
Most indexes in biology will label at least two different types of research articles:
Primary article: A primary article will directly report the authors' research findings. The details of experiments they conducted will be reported. Most primary articles follow the "IMRAD" format familiar to students from writing lab reports: Introduction, Materials and Methods, Results, and Discussion.
Review article: This type of article will summarize the research that has been done in a certain research area. Reviews can be a good entry point into reading on a particular research topic, since some terms will be defined, and important experiments and results discussed. Web of Science is an excellent database for locating reviews.