You can not search or list torrent files that are stored here, you can only access them if you already know the info_hash value of the torrent you want to download.
The way to access torrents is simple, you just use the url https://btcache.me/torrent/INFO_HASH_IN_HEX (note HEX values A-F must be in uppercase)
https://btcache.me/torrent/640FE84C613C17F663551D218689A64E8AEBEABE (Slackware 12.2 DVD ISO)
The torrent files are saved to disk in gzip format, that means you have to use a client that understands the gzip transfer encoding.
Just choose the torrent file you want to add to the cache and click "Cache!".
Enter your .torrent INFO_HASH and click "download".