If you already have an ISO image, go to Tools+Burn CD Image or Tools+Burn DVD ISO Image. A window opens in which to enter the location of the Image to Burn. K3b calculates a check sum and displays it in MD5 Sum. Make sure to compare ISO files you downloaded from the Internet with the MD5 sum provided by the source of the image. If the sums are different, the image has not been downloaded correctly.

Choose the medium and writer to use in Burn Medium. Select the speed of writing. Set your preferences, such as number of copies in Settings. Their meaning is the same as if creating a new CD or DVD from sratch. To burn the disk, click Start.