Step1: Choose a template and get into the Builder.
Step2: Give a click to the block which you want to move.
Step3: A toolbar will appear at the top of that block. Two of the first tools are arrows reading, 'Move Up' and 'Move Down'
Step4: Click on the first arrow reading 'Move Up' will move your block above the block onto it. While click on the second arrow reading 'Move Down' will move your block below the block descending it.