How do you add some color to black and white ...

cclama-

Photoshop can do this, altho I do not own or use it. It would be best to scan the photo into your computer, manipulate it, save it to a portable medium, and go print it somewhere.

If you try and mess with the picture itself, you will wind up with a mess.

JayR

One assumes you mean film photos, rather than digital. In that case, colored dyes were used like paint and were hand applied with a brush. The dyes, being transparent, allowed the detail of the photograph to show through. I VERY laborious task, and not one for those without substantial artistic skills.

One assumes you mean film photos, printed on paper.

1)- Transparent colour Dyes are available in booklet form ( Fuji transparent colours) Tear off a portion of the paper colour dye of the selected colour, desolve it in water and paint by brush, take care to start with lighter shade and slowly go up to the darker shade, or you will spoil the photo.

2)- Another way to colour your B&W photo is to use a chemical toner, for that you have to first bleach the photo then soak it in a SODIUM SULPHIDE solution, when it reaches the required depth, wash it in water and fix it in a fixer solution. You will get a sepia tone (brownish tone). Red, green, gold, blue, tonners are also available.