www.neuron.yale.edu

Here is what I want to do. Have a neuron voltage-time graph for say 1500ms. For the first 500ms I want the graph background to be light red in colour. For the second 500ms I want the graph background to be light blue in colour. For the third 500ms I want the graph background to be light yellow in colour. These colours are to denote in a nice form different segments to the simulation. BUT I am unsure how to do this. Is there any way in GIMP perhaps? I would be so grateful for any help. Thanks so much.