I've not figured out how to do it properly yet Mark so what i do is use the brush tool in Lightroom, make the pic B&W then use the brush to select the area you want in colour and choose the colour from the palette, its not ideal as you can see the soil is off colour and her top is too pale also.
Is there a way of doing it properly in LR guys?
Thanks.
Well that's not how it's done, but to be honest, I appreciate it sounds like a cliche, but leave the selective colour out.
As Shaheed said, processing is a part of the artistic process, it's not something you add 'just to see what it looks like'.
Selective colour can work (rarely IMHO), it's a substitute for lighting and composition to draw attention to something in an image. But done without any thought, it just draws attention to the wrong thing (as above).
Re my comments above, making a picture of your girlfriend should mean that your girlfriend is the point of interest, have a look at some videos regarding composition. Look for 'rule of thirds' and leading lines. Then think about contrast and light, if you place someone in a busy background, they'll 'disappear' into it. We use selective focus, or look for or create a pool of light to draw attention to the subject.
You've got an eye for the image (or you've copied without knowledge), in the first you've created a frame within the image (it's not a good fit, but the idea is right), the second uses the path as leading lines. Those ideas used better (as advised above by Paul) will make decent images, just remember what's important.