If the TV has a component video input you should use that. Better picture than composite.
You could buy an AV to HDMI converter but it makes more sense to buy a disc player (DVD or BD) that has HDMI out. It will have a better picture.
You can still use the Bose for CD playback and as a sound system for the TV connecting it to the TV optical audio output. Check the TV manual on how to use it. You may need to turn it on and turn the TV speakers off.
Thanks for your response americanaudiophile.
The TV only has HDMI and Optical so unable to use either of composite or component.
Both the TV and the Bose have optical so thats probably what I'm going to use in both.
Just another query - is there any AV to HDMI convertor which makes it 4K.
Thanks once again for the response.