2) extract bootable sector from a bootable disk
4) Create a bootable image file
Run ImgBurn
Choose "Create image file from file/folders"
Include desired files and folders
Click "Advanced", "Bootable Disc" (sic), specify as "Boot Image" file the file you obtained in step 2).
Launch the process, it will result in a .img file.
5) Create CD/DVD
Relaunch ImgBurn
Choose "Write image file to disc"
Browse to the image file obtained in step 4).
If everything goes well, you should end up with a bootable CD/DVD.