First, do some background research to make sure you know the official name of the bill and the year/Congress it was passed. A quick Google will often suffice.
Federal law is collected in a publication called the U.S. Code. You may find the text of the bill or the text of the code online, but try to find the citation for the code. It will look something like this: 42 U.S.C. § 7401
Look for a section toward the beginning of the chapter with a title related to objectives, findings, or purposes.
You can find scholarly articles on your law in the article indexes listed to the left, in LibrarySearch+, or in the resources listed below.