To set up a tattoo gun you will want to make sure you know what a tattoo gun is used for. It's to help the tattoo artist have a steady hand and makes everything easier to do a tattoo on someone. Setting up a tattoo gun has many options and can be different every time you make a tattoo on someone. You can find more information here: http://www.cooltattoofinder.com/tattooing-tips/how-to-set-up-a-tattoo-gun
There are so many different types of tattoo guns and they all have a different way to be set up. With the traditional tattoo guns or machines it is a bit easier to set them up. For step by step instruction on how to assemble your tattoo gun you should check out your manual that came with the machine.