There are two ways. Go to the blue Apple in the top left corner and select "About this Mac"->When the Finder info window opens up select "More info...". Plus, you can directly go to Applications->Utilities->System Profiler.
You may want to invest in a book about OS X. OS X is a totally different animal than OS 9! I found during my transition to OS X was SO much easier because of
David Pogue's The Missing Manual. They have updated it for Panther. Pouge's books and writings are very easy reading, humorous, and very informative! This is not a plug. I just really like this book.
Lastly, OS X based on BSD Unix and Unix LOVES permissions. Every file has a permission attached to it for the computer's (and you) safety. So, Apple stuck a little program file to Repair Permissions because all these older Mac developers still write for Apple (using Carbon) but are still a little shaky on permissions in OS X (Even sometimes Apple software writers themselves)! So, make it a habit to go to Applications->Utilites-Disk Utility and run Repair Permissions after every single software install and on a regular schedule. I can't stress this enough in PREVENTING future conflicts and headaches.
Also, IMHO opinion the best hard disk utility is
Alsoft's DiskWarrior. This application has saved my butt right from OS X beta to Panther. Warning though, an old long standing disk utility (you can figure out who by reading numerous Mac boards... even osx.com) can ruin your OS X system! So be careful.