Toast only has the ability to "span" content over multiple disks IF they are straight Data DVDs you are trying to burn- which you can see how to do in the Toast "Help" menu by looking up "spanning".
if it is not a data disk set you are trying to burn, but rather it is video content then the only way is to burn the content to a double layer disk with a double layer compatible drive or use the "Shrink to Fit" option to compress and fit the video onto a standard single layer disk.
Great news! I figured it out! I was trying to put the file in the copy>image section. But then I put it in the data>Mac & PC section and it worked! Thanks for your help and GOD BLESS!! WOOOOOOHOOOOOO!!!!!!!!!