The “Classic” in Classic Mode refers to KreateCD before version 1.0. In this mode you're able to add multiple tracks, which can be of all types. In theory it is possible to create a CD that works on a PC as well as a CD-player.
The usage of the Classic Mode is simple. You can add tracks using the Add Track button. This will open the Track Dialog where you can specify the type of track. The already available tracks can be edited with the Edit Track button and they can be deleted with the Delete Track button.
You have the possibility to move tracks up or down (for whatever reason you may have) using the Track up and the Track Down buttons.
If you have a track that was based on a directory, in where you have added files, you may select the Track Update in order to calculate the new size.
When you are finished you may click on the Write CD button to start burning the CD.