The key to understanding the Baofeng ( and CHIRP ) is knowing that its an "all or nothing" kinda thing. Its NOT a live communication between CHIRP and Baofeng; rather, its a download "clone" ( make changes ) and then upload "clone".
The first thing you want to do is to download your radio's settings ( whatever they are, even if its just the factory defaults ). Then, make any changes you want, and then upload the img file (which includes your changes).
Don't forget to save your image file ( File --> Save as )
Also, when downloading; make sure your volume is turned up at least half way... some folks say all the way !
Sometimes the CHIRP software does not appear to work because your FTDI driver is not correct if you're using Windows ! This is a pain of course. I use gnu+linux ( Mint ) and the FTDI driver just works there... no issues. If you cannot get the FTDI driver to work in Windows, you can build your own cable ( use the existing one ) by replacing the usb end with a pl2303 based TTL serial bridge, or a cp2102 based TTL serial bridge.
Best of luck to you.
'73 de W0MHH
marcus