Click on the ISO maker button in DT Panel:

The click is opening the Make ISO dialog:

Select your cd/dvd drive in which the disc is inserted you want to make an ISO image from by clicking on the Source drive dropdown-list:

After you selected the drive press on Make button to start the operation:

The click on Make button will open the Save As dialog in which you can define the location in which the new ISO image gets saved:

After defining save location and pressing on Save button, you will see the following progress bar:

After ISO maker did its job, you will see the following success message: