How to setup something like piratebox on ubuntu?

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http://ubuntuforums.org – taking inspiration from piratebox and library box, I want to share files over a local wifi connection (not via the internet): I have an old pc, a usb wifi dongle, some storage (usb stick or HDD) - share this data over wifi - I do not have a router to connect this to. The pc will not be connected to the internet its just for offline file sharing. How would I go about doing this, I assume I just need to setup the pc as an adhoc network? but how to direct visitors to the files? thanks link: http://wiki.daviddarts.com/PirateBox_DIY http://jasongriffey.net/librarybox/ (Hardware)