The save button (or Save As… on the File menu) has three uses:
Search parameters can be saved to disk to allow complex searches to be set up, saved, then recalled for later use. These are saved in files with the extension .PAR. See Format and use of .PAR files for more information on their format and usage.
Once you have set up your search parameters and performed the search, click on the save button to save them to disk. Ensure that the Save as type box on the save dialog is set to Search parameters (.PAR).
The exact contents of the search results window can be saved to disk in either HTML or plain text. Display what you want to save in the results window, click on the save button, then ensure that Ensure that the Save as type box on the save dialog is set to Results in HTML (.HTM). or Results in plain text (.TXT) as appropriate.
The matching file list can be saved as a CSV for importing into Excel or a database Set the Save as type box on the save dialog to Matching file list (.CSV).
The open button on the toolbar (or Open… on the File menu) will allow search parameter files previously saved as described above to be reloaded.
Once loaded, to execute the saved search immediately click on the 
button
To modify the parameters before searching, click on the 
button