x3 bios flash is for flashing a new bios, until you do that you cannot install a dashboard or any homebrew/backup for that matter. Unfortunately a hacked bios is technically illegal, so you will have to get the bios from the usual places. there is a great tut on xecuters website, i suggest you read it. once you flash a bios, you can use your computer to ftp your xbox and install dashboards and such.
edit: you know what, im feeling nice today...
tutorial for flashbios from team-xecuter.com http://www.team-xecuter.com/flashbios/?CMS...e0b139cd97ef0b3
tutorial for the most popular usual placehttp://www.xbox-scene.com/articles/xbins.php
make sure you download a v1.6 bios, as all other bios' are not compatible with a 1.6