Use Reshacker to import/export the graphics. Use a picture or image editor, such as Paint, (although I highly recommend fireworks). Some will say to use photoshop, but I have only ever experienced problems with it, so Im partial to fireworks.
Im not great with making custom graphics, and if youre just starting out with it, I recommend doing what I do, and either adding to or subtracting from the saturation of the hue, or by inverting the color.
In order to do this in fireworks, simply open the file, then at the bottom there is a tab called Properties. There will be a blank textbox like object, with a plus and minus button above it. Click the plus button, then select Adjust color, and towards the bottom, there areHue/Saturation...andInvert
right next to each other, then choose one. If you choose hue/saturation, it will bring up a window with sliders to set it by rolling the slider, or setting it manually.
Invert works automatically by reversing (inverting) the color schemes of the image to the opposite color on the color wheel.
Mind you, I did in fact pixel that white samurai drop/trade gfx myself. Since its white, neither of those functions will do anything to it, or anything else white, except invert, which will turn it black. So if you dont want something white to turn black, youll need to pixel it yourself.
Programs used:
Reshacker
Fireworks (official)
You need an account at adobe.com to download Fireworks. Anywhere else could be pirated software, so I wont post any other links.
Enjoy.
PS: Dont mess with the lightness of the image, itll only make it hard to see on the client. /experience
Here you go i think
Credits to Syran for the guide :)