Your photos must be in JPEG, GIF or PNG format before you upload them. JPEG is the best format for photos. You should be able to change most other image types by opening the file, then clicking save as from the file menu.
The filesize of your photo file should be less than 100k. You can check the filesize by right clicking the file and clicking view properties...
Note 1 meg is bigger than 100k. If you see the word megabytes, then your image is far too big... The average size taken by digital cameras is normally around 250-400 kilobytes. You should use your lowest settings on your camera, or VGA settings... Otherwise you will need to compress these images before you can upload them to the web... You can do this after you have uploaded them also, but a large file size will make it take ages to upload.
You can also check this if you right click on a photo file and then click "view properties".
The physical dimensions should be less than 500x500 pixels.
Preferably 320x320 pixels or thereabouts... eg 320x200 or 200x320
eg The largest dimension should be 320 pixels.
300 Pixels is approximately half the visual width of most websites.
If your photos are not in the right format or size, they may be too big to upload to the content management system or they will make your website run slowly.