I once read a similiar topic about guiGetScreenSize which wanted to place a GUI in the middle of the screen. Had to divide the height and width of the screen and then subtract GUI's height and width divided by 2.
middle height GUI = (screen height)/2 - (GUI's height)/2
middle width GUI = (screen width)/2 - (GUI's width)/2
That starts making some sense.
But seeing that you don't want to have it in the center. I'm sure you saw the dxDrawText wiki page. There you see this:
local screenWidth, screenHeight = guiGetScreenSize() -- Get the screen resolution
[..]
dxDrawText( playerZoneName, 44, screenHeight-41, screenWidth, screenHeight, [..]
This might come helpful?