Your images should be sized correctly before being uploaded
The ideal size is 300 x 226 pixels.
This is a natural reduction (constrained proportions) on a standard photo
and can be achieved using any graphics software.

I do however recommend the use of a bit of free software
Easy Thumbnails which I find very useful.

Please note however the site will automatically display the proportional image height for a breadth of 300 pixels.

Once complete save each image as a Gif or Jpg with a name which is unique to you.