The first listbox lets you pick whether you want to search recent news articles, or web pages, the second picks the display format.
The first entry box is for the query, the second for the keywords list.
It's a link to the altavista advanced query, which is a full boolean search engine. Basically this means that you can construct simple powerfull queries.
Some query examples
linux~SVGATex* This searches for a word beginning SVGATex near any mentions of linux. (The case of SVGATex must be exactly matched, if you want it to match any case, use lower case only)
(moosehead~sled)&!beer This searches for the word moosehead, near the word sled, but excludes pages which mention beer.
"holy grail"~(sound|wav|au)!~dead Search for the string "holy grail" occuring near sound or wav or au, but excluding matches that have dead near them. This would likely pick up lots of monty python sound clips, from the film "the search for the holy grail" excluding the "bring out you'r dead" and "I'm not dead yet" clips.
Adding words to the keywords line, brings matches containing those words to the top of the list.
For more help, and for better understanding of how the search engine works,
see altavista, entering a blank query, then selecting help from the
imagebars up at the top will give you some more tips.