Things You'll Need
Instructions
Open a copy of the black and white image in your photo editing software that supports layers.
Go to "Image." Click on "Mode" and change the mode to RGB.
Click on "Layer" then "Duplicate Layer." Select "As background copy."
Highlight the background copy layer in the layer dialogue box. Click on the "Lasso" tool and draw a selection around the area you wish to color.
Click on the foreground square, the white square partially on top of the black square in the lower portion of the vertical tools bar. This will bring up the color picker.
Select the color for the selection and use the paint brush tool to color the area.
Click on "Layers." Click on "Add Layer Mask" and click on "Reveal All."
Click on the tiny black and white squares to return the foreground and background to white and black then click the double-headed curved arrow to switch the foreground to black.
Set a small paint brush to 50% hardness and carefully brush around the colored area to eliminate any color outside of the area.
Repeat the process for any other area you wish to color. Make a new layer for each area to be colored. When you are satisfied, save the file as a "PSD". Then go to "Layers" and at the bottom of the drop-down box, click "Flatten the Image." Save this file as a "Tiff."