how do u outstand a certain colour in PS like this photo
do u want to do what they did in that photo? What they did is destaturate everything but the railings. You'd have to select the railing (takes some practice to get it perfect) and then copy to a new layer. Then desaturate the layer below (the whole image). Or you can select the railings and then "inverse selection" and desaturate. Whatever is easier for you.
There's always more than one way to do the job in photoshop. practice on pictures.
Do what BackLash said-use the magic wand tool to grab the areas you want in color or vice versa.
Paint the room in "grayscale" except for the parts you want in color then take a picture.