CONVERTING TO SINGLE TONE
First convert your picture to B/W using either method mentioned earlier. Then press F7 to open a layer window at the bottom with your picture as the background. Create a new layer using the icon at the right bottom (hover your mouse over the icons to find out what they are). Then go to tool bar on left side of the screen. Click on the Set Background Colour tool (depicted by an icon of two boxes overlapping each other). Select a colour from a palette. To select colour in the upper window, press Alt + Backspace. To select colour in the lower window, press Ctrl + Backspace. Then go back to the layer window. In the options, click on Normal, which opens up a dropdown menu. Select type of single-tone effect you want in your image.