Right click on the image file for your pictures. A box will appear next to the arrow, and scroll up (or down) to the bit saying "Open With". Another box will then appear and scroll across and left click on "Paint". There should be a toolbar just above the area where your image is and click on "Image" (it should be the 4th one along). Click on Image, and then scroll down to "Stretch/Skew" and click on that. Change the values in the top 2 boxes (the stretch ones) to 30%, and then click on OK. Hopefully the size of the images should be Ok now. Then you can save the file and upload it.