HOW TO...a colored and Black & White photo in one??

I'm using the same photo, just for example. If your image that you want isn't B&W, convert it so it is by using a B&W layer mask or desaturating. I positioned the B&W over the color layer and added a layer mask to it.

You need to make a selection of your color subject. This will vary depending upon your subject. For mine, I used the blue channel as it offers the most contrast between the dog and the couch. I duplicated the blue layer:

Using Levels, I increased the contrast to make a good selection between the dog and the couch.

Clicking on the channel thumbnail while pressing ctrl, made a selection of the channel:

Now using a black brush with the layer mask selected, I paint out the area of the color dog:

Now deselect the selection ctrl-D and use a brush to feather the B&W image into the color image.

To lighten the B&W, make a curves adjustment layer and clip it to the B&W layer by clicking between the adjustment layer and the B&W layer in the layer panel while holding the alt key. Then grab the shadow end point of the curve line and raise it to lighten the blacks.