What you being asked to do -- summarize and evaluate several sources that you may use in a research paper -- sounds to me like an annotated bibliography. Each entry in an annotated bibliography should focus on one source and should include three items:
1. The citation for the source (using the correct citation style, as determined by your instructor or the course subject: e.g. MLA in English and other language courses, Chicago Manual in History courses, and APA in Psychology, Education, and a number of related courses.
2. A summary of the source, usually at least one paragraph in length. Keep your opinions, criticism, and praise out of this section.
3. An exaluation of the source, usually at least one paragraph in length. Focus here on how the source may or may not be useful to you in developing a research paper on your selected topic. Your opinion is allowed (even welcome!) in this section.
Below I've given three links to an extensive discussion (at OWL at Purdue) of annotated bibliographies. This resource includes three developed sample annotated bibliography entries.
Before I end, let me add that your topic sounds a little general. It's okay to have a general topic at first, especially if you don't know what particular focus you'd like to have in the research paper, but in order to find good sources, you'll need to focus your subject and use meaningful key words in your search for sources. For example, you might be interested in trends in caring for the elderly in a particular country or among members of a particular population, or you might be interested in exploring how the meaning of aging may be changing with medical advances (e.g. "youth" and longevity doctors).
I hope these examples help!