To find out information about federal legislation, including public laws, you can use the website Congress.gov. If you want to know about a bill or law that is from the current congress, you can simply type in a few keywords or the bill or law number (no spaces).
Examples:
"no child left behind"
hr933
pl114-38
If you aren't sure what Congress introduced or want to search older material, first change the drop-down menu on the left to "All Congresses" and then type in your keywords/bill/law number.
Once you get to your results, click on the bill number to view full details.
Click on the tabs (like "Text" to see the full text of the bill, "Actions" to see what has happened to the bill, and "Related Bills") to find out about related legislation.