well seen as ive been asked by a few who doesnt understand the art of resizing without streaching the source here is just something quick ~
and ratios are easy enough to understand...there isnt a set rule as to what ratio you do but instead you should just go with whatever it comes in from the image ~
heres an example ~
firstly make a new canvas ~
next bring up your image ~
obviously its too big so you need to resize it (okey just pretend that its been extracted)
go to image>>> image size and the box should pop up ~
heres the important bit when resizing ~ you have to make sure that the "constrain proportion" box is checked when changing one of the values ~ in this case seen as my sig is 400pix wide i will make the image 250 pix wide...
notice the change in size and all that is left is to just drag the image into the other empty canvas...there you are done :3
all you need is a BG to fit ^_^