To find the case, type this in the "type a citation" box, which should be on the first page after logging in: 490 U.S. 228
That citation identifies the Price-Waterhouse case. It means that if you were looking the case up in a law library, you would find it in the 490th edition of the U.S. Supreme Court Reporter, on page 228.
For the second part of the question, you would go to the research system link, then click on the search tab. It sounds like your prof wants all cases mentioning Price-Waterhouse, so click the box next to Federal & State cases, Combined.
Then click go.
In the box, type (INCLUDING QUOTATION MARKS, and make sure you put v. not vs.) "Price Waterhouse v. Hopkins" and click search.
You will get over 3000 results.
You don't. You can mow your own lawn too. But a landscaper might do a better job of making your yard look nice.
In this case, a patent lawyer might know that what you are looking for isn't really a potato peeler. What you are looking for might be called an organic produce outer layer removal system. Since the patent doesn't include the words potato or peeler, your search wont find it.