Go to Add → Container to create a new Container element.
Change its Type to Columns. This will split the container into two columns of equal width.
(Optional) Adjust the widths of the columns as needed (or add additional columns).
Drag and drop your elements into each column.
You're done! Note that the resulting container will automatically adapt to mobile displays (see below), but should you need more control over how it adapts simply toggle Mobile Settings to Manual (under Appearance).