Thread:JmLyan/@comment-24912131-20150812010211/@comment-7481207-20150824073815

First open the picture in the program of your choice (I personally recommend Paint.NET, as it is free and simpler than the others). Then locate the black & white tool from the menu bar (Image -> Adjustments for photoshop or Adjustments for Paint.NET). Photoshop will show options when you click Black & White, but those don't need to be changed. Then create a new layer in the layers window (located at the bottom right, use the leftmost button for Paint.NET and the second button from the right for Photoshop). Now fill your new layer with a color or gradient. Then change the blending mode of the new layer to "Overlay". In photoshop, this is done with the drop-down box at the top of the layers window. In Paint.NET, double-click the layer and use the drop-down box in the popup window.