Finder allows you to browse, move, and open your files (either those on your hard drive or a network share). It also gives you access to all of your programs.
A typical finder window. In this case, it is displaying available programs (applications).
Changing views
Finder has three ways of displaying information: icons, list or columns. Switch between them by click the appropriate button (see below)
Different views are appropriate in different situations. Experiment a little with all three and see what works for you.