[...] Im Handbuch und Hilfemenü habe ich nichts darüber gefunden. [...]

Offenbar hat man bei Xara/Magix "vergessen" den Teil in die Übersetzung zu übernehmen... 😜

Im englischsprachigen Original findest Du eine (fast) vollständige Anleitung.

Die Anleitung ist leider auch unvollständig, weil hier die Angabe des Aussehens (Farbe) und die Position der angesprochenen Buttons fehlen. Aber mit ein klein bisschen Experimentierdrang ist das leicht zu kompensieren.

Probier's mal.

Viel Erfolg

P.S.
Hier der vollständige Text, den Du kopieren und drucken kannst:
---------------------------------------------------------

Table SmartShape

The Table Smartshape is a simple table which supports basic table insertion and editing, including adding, removing and resizing rows and columns, various table formatting options and automatic formatting of the table to fit contents. You can also paste data from other sources like Excel and Google spreadsheets to quickly populate a table.

Find the tables in the "Insert" menu, or in the Content catalog under "Components" > "Print & Web Components" > "Tables", where you will find a range of designs.

Table Handle Summary

Hover over the adjustment handles to see what they do. They are...

Padding
Drag to adjust the Outer padding, the Inner padding and the Cell padding

Select/Reposition
Click to select columns and rows - drag to reposition them

Add/Remove
Drag to add or remove columns or rows.

Show/Hide caption
Click to show or hide the table caption title - edit using the Text tool

Column width
Drag to adjust column widths

Row height
Drag to adjust the height of the rows

Resize
Drag to scale - Ctrl + Drag to stretch. Drag to stretch either horizontally or vertically.

Cell borders and merging cells
Select a cell, range of cells, row or column - then click on the green blob in the corner of the selection to open a cell border menu.

The first 4 controls represent the four edges of the selected cells. You can click to highlight any, or all, of them. In the above case the right edge is highlighted. If you now adjust a line value, say to select a line width of 2pt, it will apply the line to the right edge of the selected cells.

To merge adjacent cells into a single larger cell select two or more adjacent cells, and click the Merge Cell icon - the last one on the right of menu. Merged cells can be restored back to their original un-merged state, by clicking the same control again.

Note: only while the Border Control UI is visible does applying line values affect the selected edges. if you close the border control, then applying a line width, or line color, it will apply to all 4 edges of the selection.

Adding rows and columns
When you add a row, the last row of the table is duplicated to create the new row. If the table has different background colors for alternate rows, that formatting is maintained as you add more rows. Adding columns works similarly. If the table cells contain embedded objects or symbols however, then these will not be duplicated. Select rows and columns, or ranges of cells using standard Ctrl and Shift keys.

Deleting rows and columns
Drag the row or column orange select handle outwards, away from the table. At a certain distance a red cross will appear, if you now let go, the row or column will be deleted.

Table cells
Each table cell has a text column and a background shape, which determines the background color of the cell. Use the Text Tool to edit and format text within the cell, just as you would edit any other text. You can also place any other type of object in a table cell by inserting it embedded in the text. To do this select and copy the object you want to insert to the clipboard, place the text cursor in the cell and paste (Ctrl+V). Select multiple cells using Shift + select or Ctrl + select

Colors and tables
The table as a whole has a background color and that determines the default color of each table cell. But each cell can have its own background color and you can set the color of a whole row or column of cells.

If the table is not already selected, the first click on the table will select the whole table (you see all the table's handles appear). Click on a color to change or replace any of the colors used in the table. The Replace color dialog will appear allowing you to choose the color to replace.

You can also change the color of all cells in a row or column by selecting the whole row/column. With the whole table selected, click on the row or column's Select/Reposition handle. That selects all the background shapes in the row or column. You can then set the background color, or reset the background color, of all the selected cells.

Outlines
With the whole table selected, the line width control on the top bar shows the width of the cell outlines for the whole table. You can change the outline width using that control, or remove the visible outlines by selecting None.

To set the color of the outline, right-click on the Color line and choose Set line color. You can also select the line colors in the same way as cell backgrounds, by selecting the color and selecting Line color in the replace colors dialog.