You have the image in the div correctly.
In the elements list, select the div block with the image.
Then, in the div’s details, slide down to the typography sections and select “center” as you would for text.
That centers the image in the div.
You can use padding within the div to move the image right/left or up/down as desired.
For divs, you can float content left or right, but not centered, so you need to use the text-align:center css to do it. Just select the div then for the attributes, use the text-center icon to do it.