Help Loading Screen

So.

i want to change the loading screen( i know how to do that , not a problem)

the problem is the size and position of the image when the window opens

what i mean is

my screen resolution is 1366x768

i make an image (1024x1024) : http://prntscr.com/g99bz0

and when the client opens looks like this : http://prntscr.com/g99deu

it centers the image and adds black on left and right.

so i thought

if i make a bigger image ( more than 1366x768 ) it will cover the whole screen and whatever is left outside it will be fine PLUS on bigger screens it will show the whole image.

so i did this : http://prntscr.com/g99ffi

the problem is that it didnt really like my idea and did the same thing again...  image still starts centered but it gets a SHARP CUT when it goes to 1024 pixels BUT the counting doesnt start from top left of the window it starts AFTER it centers the image around 190-200 pixels from top left of window : http://prntscr.com/g99deu

i need information on how to make the image start from top left and not be centered

any help is welcome. thanks in advance