How do I decide what I need from everything I've found?

As you organize your information make sure you keep focused on the essential question of your research topic!  This essential question will help define the main point of your research. If you're writing a paper this is commonly referred to as the thesis statement.

Once you have finalized your research statement, review your information sources to develop relationships between your data and research statement. Then review and organize this information to best support your research goal. A few methods to do this include: compare and contrast, advantages and disadvantages, starting from a narrow premise and building on it, cause and effect, and logical sequence.

Finally weed out any information that does not support your research statement and continue searching for any information that you feel you need to fill in the gaps, or that complete and support your research statement.