Insert a blank disc in your optical drive for the burning of the ISO file.
Free ISO Burner supports all standard types of CD, DVD, and BD discs. However, you should use an appropriate size of empty disc per your ISO image. For example, an ISO file that's larger than a CD but smaller than a BD should be burned to a DVD, and so on.
You can reference this Table of Optical Media Storage Capacities if you think that information might be helpful in your decision.
