For this demo, I'll assume you have extracted the data in /local/. You may need to change the paths accordingly if you put the data somehere else.
Currently, grass 6.2 is installed on all the lab machines. To get started, type grass62 -text at the command line. You'll be presented with a screen that asks for a LOCATION, MAPSET, and DATABASE. For LOCATION, enter NCdemo. For MAPSET, enter your login name. This will create a subdirectory under /local/NCdemo where files you create will be stored. For DATABASE, enter /local/ or the path where you extracted the NCdemo data. Then type <ESC>-<ENTER> to start using the data in this LOCATION.
Grass commands begin with g., d., r., or v. to indicate the command is a general command, display command, raster command, or vector command, respectively. Each grass command is a UNIX executable, and the GRASS terminal is just like a standard shell with TAB-completion, so if you hit g.<TAB> you can see the list of all g. commands. Almost any command will give you usage instructions if you specify the -h flag, for example d.erase -h. Let's look at a few more g. and d. commands.
The g.list command shows you what raster or vector layers you have in your current location. Try typing g.list rast and g.list vect. You should see the names of files you displayed earlier. Each layer has it's own spatial extent. The county layer covers the whole state while the neuse500 layer only covers the Neuse river basin. The viewing window you created using d.mon x0 also has a separate spatial extent. You can change it by running d.zoom to zoom in and out. If you ever get lost while zooming, you can set the display window extent (also called a region) to the region of a known layer. So g.region rast=neuse500 will reset the region to the boundaries of the neuse500 data set.