How to do a Differential backup?

Before you can do a Differential backup you have to complete at least one Full backup.
Before you can select the Differential backup method, you first have to complete Select Source (step 1) and Select Destination (step 2). Once you're in Select Method (step 3), you have three backup options; Full backup, Differential backup and Incremental backup. Click the radio button next to Differential backup to select this method.