Code sections are often indicated in the margin of the public law. If you know only the name of the act, check Shepard's Acts and Cases by Popular Name, including the paper supplement. News, U.S.C., U.S.C.A. or U.S.C.S. Look at legislative history notes following code sections which will refer you to the public law number and the citation for Stat. All of these indexes will cite both by subject and by the title of the bill or act. Check the Digest to General Public Bills or the CIS Legislative History volume.
Private laws are acts passed which affect one person or entity.
For example, an act may be passed settling the monetary claim of a private citizen against the United States government. A few private laws are passed every Congress. Private laws are found in the bound volumes of Statutes at Large.