Are you connecting this to the computer with a "serial" cable or is it through a USB adaptor? NORMALLY using the "autodetect radio" function on the SELECT RADIO menu will get it all set up.
IF it can't find the radio the most common reason for this problem is .... make sure the radio has the PC Control set to SOME baud rate. The radios come out of the box with PC Control turned "Off". You have to go through the MENU about 3-4 layers down to get to this. I'd suggest setting for 115Kbaud
Look at Page 50 in the BC396 owners manual.
You can download the 396's PDF manual here. I find it's a lot easier to use the search functions to find topics of interest as compared to shuffling through the pages.
I searched for "PC COntrol" and went right to it on second "find".
I Did the install.. Can't detect the radio.. Not on serial or USB hookup.. It's a BC 396.. Help pages not much help so far.. What have I missed??