chances are you have the file saved in bitmap form. open paint, go to file, hit 'save as' then select '.jpg'. it'll be much smaller, guaranteed, unless the picture is huge, in which case, shrink it by going to the image tab and clicking 'sketch/skew'. make it smaller by setting the percentage or the original dimensions (i.e, if you hit 50% and 50%, the length and width will decrease by half)