There are plenty of places to get more on the basics on GDP. Here are a few of them:
The Bureau of Economic Analysis. The BEA, which puts out GDP statistics regularly, is a great place to go for the basics. The latest GDP news release can be found here, and there are also a wealth of other documents: a guide to the National Income and Product Accounts, a look at the methodology of counting GDP, and a rundown of GDP by industry, complete with an explanation of how GDP and gross output differ.
Information on a no-growth economy. It’s a fringe idea, but some people think it would be possible to have an economy in which there is no growth. See the basics at the Center for the Advancement of a Steady State Economy.