You Should:
State YOUR research topic and hypothesis and how these three articles are relevant.
State the research topic of each of the three articles
Review and explain the research question(s) (or hypotheses) that guided the three research articles,
Identify the independent and dependent variables of the research articles,
Briefly describe the method used in each of the studies,

Identify the measurement and experimental operational definitions (i.e., identify how the researchers operationalized the independent and dependent variable) for each of the articles, describe the results and conclusions. If one of your articles has more than one study, you only need to

Summarize the study that is the most relevant to your hypothesis.
give your opinion about the research (e.g., criticisms or questions about the research, experimental

Design, ect., or ideas about other interesting research questions not addressed in the article). Importantly, however, here you must also think specifically about how each research article informs your thinking about your hypothesis.

Give a summary of how the three articles combine to inform your thinking, and describe very briefly (one paragraph should be enough detail) what you plan to do for your research proposal (e.g. tell me what your 2 independent variables will be, and what your dependent variable will be).