here is another method I sometimes use
1. open your photo
2. enlarge it by scrolling your mouse wheel
3.pic your selection tool. I use freehand smart edge
4. slowly click around the edges of the part you wish to separate
5. once you have completely traced the subject,
6. choose selections, invert
7. your selected area is now the part around the main subject
8. choose adjust, hue and saturation,then colorize
9.then slide the sliders all the way to the left removing all color from the background, click OK
10, you should now have a colored subject with B&W background
11. right click anywhere in the pic toremove your selection tool
12, save copy as, to avoid losing your original