JPG, jpeg, bitmap, gif, etc are types of image files ... bitmap being the largest... JPG or jpeg are the most common accepted. If you want to see what I mean... go into your paint program and make just a small colored square and save it as a JPG then rename it and save as a Bitmap ..then go to the pics and mouse over to see the size difference... then of course delete them... unless you have further use for them lol

Right click on the Pic you want to use and right click. When the box pops up click on "Open with"
then find your paint program from the list that comes up.
After paint has opened with you pic, click IMAGE - then "Stretch/Skew"
in the top 2 boxes enter 50 (this will make you pic 1/2 the size it was, then save...
If it is a BITMAP photo, that may also be your problem (too big of a file - bitmap being the largest) save it as a JPG or jpeg
and delete the bitmap. This will not change the texture of the pic... and JPG - jpeg are most commonly used
Hope that helped