Hi Jeff and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
It is quite complex to make a bootable DVD of El Capitan. Rather than trying to make a bootable DVD, I'd recommend to make a bootable USB El Capitan drive.
To do that,get a 8GB or more USB flash drive (make sure you don't have any important files on this drive as we need to erase it)
Then download this application Disk Maker X, open it and follow the onscreen instructions to make the USB. It is a pretty straigh forward process and will only take less than 30 minutes to make it.
Download Disk Maker X from here --> http://diskmakerx.com/
You need to download a copy of El Capitan to your Mac from App Store for Disk Maker to work. So do this from the computer that you have already downloaded El Capitan installer.
Let me know how it goes
Hi Jeff, I'm just checking. How is it going ?