I think you need to make the canvas 450 x 175 pixels or smaller. That will make it easier as there will be less pixels. To resize image on pain if you dont already know go to image>attributes> there will be two boxes. the one on the top enter 450 and on bottom one enter 175 and click ok. work on it a bit before you post my sig is my first pixel w.i.p and you don't want to know what it started like!