Question

How did Supreme Court rulings give the federal government greater power ?

Answer 1

I would know about John Marshall. He was a federalist supreme court chief justice. He gave more power to the government by taking a loose construction of the Constitution. So basically he said, "If it doesnt say we (Fed Gov't) cant do it, then we can)". 
Know about these Court cases 
Gibbons V. Ogden 
McCullough V. Maryland 
Fletcher V. Peck 
Cohens V. Virginia 
Barron V. Baltimore- this one is hard to find, so basically it just said that because the Bill of Rights was a Federal decision, it didnt apply to the states. 
The rest are really easy to find out about, and you could type in John Marshall and it would probably give you all of these. 
http://www.ushistory.org/valleyforge/served/marshall.html 
http://www.lawnix.com/cases/gibbons-ogden.html- heres gibbons/ogden