How do I do selective colour in PP?

OK ... I do very little PP and normally use just OM2/OV2 for cropping and occasional fiddle with the contrast.

If you look at this you'll see an image of mine with a coke-can in the right foreground. I processed this one a little more.

In the original colour image, the coke can is of course red. What I'd really like to be able to do is retain the red colour of the can while the rest of the image is mono.

I have the RAW file available, and I do have The Gimp, RawTherapee and UFRaw installed.

I don't & am unlikely to have Photoshop.

Any pointers please?

 

OOPS ... should have posted this in Image Works ... can a mod please move it ?

 

Thanks for moving the thread Brian ... thank you also for the offer of your help, which I do appreciate ... I hope I will not sound ungrateful when I say I would prefer not to install any demo software (I presume it will become useless in some way after 30 days, & I really only use free and/or open-source software) ... also if I can learn to use Gimp etc then I have the option to edit on my Linux laptop when I'm on the move too ...

 

@Djarum -- thanks ... I'll have a look and see if I can follow the instructions given