I stumbled on to part of the answer. It looks like you are using Yahoo's service. So I figured out how to display NASDAQ and S&P 500 using "^IXIC" and "^GSPC" respectively. However, when I follow the same logic for the Dow Jones Index and Dow Jones Composite ("^DJI" and "^DJA") I get an error for the former and no data for the latter:
Apple Inc.
408.38
+2.918
Exception occurred - Please check web service URL within settings.
^DJA
0.00
N/A
NASDAQ Composite
3289.99
+20.34
S&P 500
1585.16
+6.37