GIMP gradient tutorial
Create the gradient
In the main GIMP toolbox double click on the Fill with a colour gradient.
This opens the Gradient options box, here you are presented with various options for your gradient.
If you click on Gradient a dropdown list of set gradients will appear that you can use for your image. The default is FG to BG (RGB), which we will use here.
Double click on the Foreground colour in the main GIMP toolbar and pick or type in the hexadecimal code (in this case 55aaee in the HTML notation box) for the colour you want in the Change Foreground Colour option box.
Now double click on the Background colour in the main toolbar and choose the colour you wish to graduate to (in this case 003366).
Download GIMP 