iPhoto question: burning "album" to disc

I am new. I have created a new album in iPhoto with about 20 pictures. I want to have them printed by Costco. I found I cannot drag the photos one by one, or any other way, onto Costco's order form. Nor was I successful in dragging them onto a disc I inserted in my Mac. Is there someway I can transfer the photos in the "album" onto a disc (or better yet onto Costco's order form)?

goto your desktop
then in the menu bar finder>file>new burn folder.
This will put a folder onto your desktop, then drag all pics into it. With the disc inserted press burn.
viola

For Costo's order form:

1. Open iPhoto and select the pictures you want.
2. Drag them out onto the desktop
3. Create a folder and put the pictures on the desktop in the folder
4. Now go to Costco.com.

If Costco needs you to send a folder of pictures as a ZIP file, just right-click on the folder and choose "Compress." Otherwise that should be all you need.