What do democrats believe in?

You can take a look at:
http://www.democrats.org/issues

Regardless of what their web sites say, there is no one agenda supported by all Democrats (or all Republicans for that matter). Generally what both believe in depends on where the money came from that paid for their last election and the demographics of the areas they represent to a somewhat lesser degree.

Politics can be understood much better by watching what politicians do than by listening to anything they say.