You need a cell phone that BitPim can talk to (details).
You will need a cable that plugs into your computer and into the cellphone. The page for your cell phone lists details of the cables.
If you use Windows, a driver is required for your cable. The driver should be supplied by the supplier/manufacturer of the cable. Drivers may also be available online from the manufacturer of the cable or the phone. The "section" of the help pages for your phone may have pointers to these drivers. Mac OS X and most recent Linux distributions include the drivers, if required.
BitPim Online Help built 17 January 2010