You can browse in the library's reference section or the stacks. If you know the call number for an area you are interested in, you can go directly there and browse.
Here's more on the Dewey Decimal System, including 100's and 1000's breakdowns
Here's a more basic chart of the Dewey Decimal System by 10's, in PDF (below)
Direct links to full-text entries from over 900 published reference books.