Open the “My Websites” section in your mssg.me personal account, you can go to this section by clicking here
Click on one of the created sites
Open the “Edit” section
Hold your finger (or the left mouse button, if you are logged into your personal account on a computer) on the icon with two horizontal lines placed to the right of the block you want to move
Hold and drag the block to change it’s position
Also for move a block, you can select it by clicking on it, and then using the “Up” and “Down” buttons that located at the bottom of the page, move the block to the desired location.