will iOS8 work on a iphone 4 and if so how do you get it?

No, it won’t.

(127007)

I think it will only work with iPhone 4S and later, not the 4 itself. A member of my family is running it on a 4S with 16Gb, and the phone is very slow and laggy, so I would't recommend it unless you really really want one of the features offered by iOS8.