The album allow you to upload pictures to this site to share with other users, the maximum size allowed is 800 x 600 pixels and a file size no bigger that 128k. this is much smaller than comes out of the average digital camera but ideal for displaying on a web site.
The easiest way to resize and image is with the Microsoft Image Resizer power tool which you can download free from here
Once installed just right click on an image, choose resize and click 800 x 600, this will create a copy of your image the correct size for this forum.