InDesign documents are displayed as spreads (the print layout). Generally, two pages will be layed out side-by-side. There are a number of ways to navigate around a page or between spreads.
Scrolling a Document
Click and drag the document in the Document View to scroll around the visible pages.
Click the Change Page buttons to step forwards or backwards between pages.
Go to Page
Enter a page number into the current page display and then press return to go to a specific page number.