I'm a bit of a newbie too, but I would do this first. Save the file to your Home directory. (you must have the program "Ark" to do this) right mouse click on the zip file and press extract all, make a folder and name it, press okay. Now open your folder and thats all I know.
Now I'm using KDE and Xandros File manager, not Gnome and what Gnome uses as a file manager. But you might find something similar.