double-click the placed table - the table/editor should open up in the lower part of the dockwindow

enter the table name into the corresponding field

change to the columns-tab of the table editor

enter a column name (use proposed id<tablename> as PK-Col)

add a few other columns (different col-names and types)

close table-editor by klicking the close-icon in the upper right corner of the table-editor