Can anyone help me with what this method is called and where or how i can do it. I have seen some pics that are black and white and the people in the pics their outfits are in color how is this done?
I don't know that the technique you describe has a name. In film only days it was usually accomplished with a black and white print which had color added to parts of the image with oil colors originally used to color B&W portraits.
In digital if your original is B&W in an application like Photoshop, you first go the Image menu and change the Mode from grayscale to RGB. Then you can use a brush for painting in fine detail or the Lasso selection tool to outline what you want to color and then use Fill, selecting the Color Mode to fill any color you select from the Color Palette, using a paint brush you also use the ColorPicker/Palette to choose you color and in the brush setting choose the Color Mode which applies color but preserves the underlying image densities of light and shadow.
The alternate is to begin with a color picture and again use the lasso selection tool to outline what you want to remain in color. Then in the Selection menu click on inverse, and go to the Image/Adjustment menu and click on desaturate.