1You should ask for a CDInfo to see if the disc is empty or not (handle OnDoneCDInfo).
2If not empty, you should import a track using ImportIsoTrack (handle OnDoneImport or OnDoneImport2).
3You should now create a NeroISOTrack object and add to it whatever folder hierarchy you want and optionally add the imported folder structure.
4Finally, you should call BurnIsoAudioCD.

What do i have to handle on OnDoneImport?

i am using neroCom and c#

What do i have to handle on OnDoneImport?
What do you mean? OnDoneImport[2] gives you access to the file/folder hierarchy of the imported track which, when merged with some new content and burned, gives you a new track with new files and reference to the old ones.