I want to create a gamebook where I can set a global variable on one page and use it on another.

My only successful test was that on one page I used the Set Variable script to make a variable called data.testvar equal to 1 and then used that info on another page.

Is "data" and object that always exists for every game book and does not have to be created?

If I wanted to have a variable setup where earth.continents = 7 , how would I create a variable called earth where I could make this happen?

Is there a website where basic questions like these can be answered for gamebooks created with quest?

I don't know about Quest, but have you taken a look at Squiffy? It's designed for making gamebook style games. The docs section on variables is here:

http://docs.textadventures.co.uk/squiffy/attributes.html

Thanks! I will try Squiffy too.