The spires search function merely passes your search queries onto the Spires web search, so you should build your queries in the same way, except omitting the find or fin command. This help page will only give a brief introduction to the search queries. More extensive help on searching Spires can be found on the page http://www.slac.stanford.edu/spires/hep/help/index.shtml.
Your query can be composed of several parts, combined using and and or as logical operators. Each part is composed of a letter or word indicating the type of field to search, followed by a space and the text to search for.
The following list shows some of the field indicators that can be used:
Example queries: