Searching is done as ANDs. This means that each criterion narrows the search, not expands.
Search by tag:
Just type the tag, with underscores into the box.
To search for multiple tags, leave a space between them.
To search for posts that DON'T have a particular tag, prefix it with 'NOT:'.
Examples
ranpha_franboise - find all posts with Ranpha in them.
ranpha_franboise milfeulle_sakuraba - find all posts with both Ranpha and Milfeulle in them.
ranpha_franboise NOT:milfeulle_sakuraba - find all posts with Ranpha but without Milfeulle.
Search by user:
Add the username, prefixed with USER: or NOTUSER:.
Examples
USER:desumeade - Find all posts by desumeade.
NOTUSER:desumeade - Find all posts not made by desumeade.
Search by rating:
Add the rating, prefixed with RATING:. You can also use RATING>: and RATING<: to search for ratings above and below the one specified.
Examples:
RATING:safe - Find all posts rated 'safe'.
RATING>:unrated - Find all posts rated either 'safe' or 'questionable'.
Search by image size:
Use any of the following, with the option to add > and < as suffixes to search for values less than or greater than the one specified.
Examples:
WIDTH>:1024 - Find images with a width greater than 1024 pixels.
HEIGHT:800 - Find images with a height of exactly 800 pixels.
PIXELS<:40000 - Find images with a total pixel count (width x height) less than 40000 (800 x 500).
All of the above can be chained together with spaces to search for posts that match ALL the criteria.
Examples:
ranpha_franboise USER:desumeade - Find all posts with Ranpha in them, by desumeade.
ranpha_franboise NOT:mint_blancmanche NOT:milfeulle_sakuraba NOT:forte_stollen NOT:vanilla_h NOT:chitose_karasuma NOTUSER:desumeade RATING:safe WIDTH>:1023 HEIGHT>: 767 - Search for all posts with only Ranpha (and none of the other GA1 characters) by anyone other than desumeade that have been marked as safe, and are greater than 1024x768 in resolution.