• Run HRDLogbook (the program)
• Press the button "Options" or "Configure -> HRDLog.net"
• Uncheck "Use HRDLog.net test account"
• Type your Username (your callsign) and your Upload code (you have received this code via e-mail, this is NOT your password)
• Check "Upload every time a logbook entry is added, ..."
• Check "On Air: Regulary upload Frequency, Mode and Radio" if you want publish these data on HRDLOG.net
• Press the button "OK"
• If you have problem take a look at the "Logfile" (Menu View -> Logfile)

Source: http://www.hrdlog.net/docs/Autoupload.aspx