It would help to know which format the pictures are in.
Put the disk in the CD/DVD drawer and click on My Computer (probably on your desktop) and double clck on your drive icon. You should then see a list of the photos on the disk. Go to 'View' at the top left of the window and click; in the drop-down box change the view to 'Thumbnails'. You should then be able to see all the pictures. Right click one (it doesn't matter which) and this should open a box at the bottom of which should say 'Properties'. Left click that and you should get a description og the picture type, saying something like JPEG, TIFF, BMP. If that is the case, then you should be able to click further up the box on the 'Send to' and choose 'mail recipient'. If you want to send several pics, hold the control button down whist clicking on all the pics you want to send. They should all be highlighted by then and then pick the 'send to'/mail recipient.
If the pictures are much larger than 500 KB each then you may get the choice of getting Windows to reduce the size before sending or leaving them as they are. Try sending one or two to yourself to get the hang of it.
You mentioned that you thought they had their own viewer, so it is remotely possible that the recipient may not have a suitable viewer to see them, in which case you would need to open each in a programme like PhotoShop or PhotoPaint and save them each in the JPEG format first. Let us know how you get on.