You can create complex tables by splitting and merging cells both vertically and horizontally. In addition to this you can also nest tables inside one another to create even more complex structures. (To nest a table just insert a new table in the cell of an existing table.)
1.Click in the table to select it.
2.Click in the row where you want the table to split.
3.In the Table tab select Split - Split Table. You can change the row number where the table is to split manually if you like.
Note: You can only split tables, you cannot join them.
1.Select the cells you want to merge (you must select at least two cells).
2.Use the Merge Cells tool in the Table tab or right-click and select Table > Merge Cells in the context menu.
You may need to adjust the width of the table or individual columns after merging. Remember to check your column lock settings with the Lock Column tool in the Table tab after adjusting widths.
1.Select the cells you want to split. If you just want to split a single cell click inside the cell, it is then selected automatically even though it is not highlighted.
2.Use the Split tool in the Table tab or right-click and select Table > Split Cells in the context menu and choose Vertically or Horizontally to choose the direction of the split.
3.Enter the number of columns or rows you want to split into (the default is 2).
This function restores the original number of rows and/or columns in the selected cells, basing the number on the original definition of the entire table.
1.Select the cells you want to unmerge. If you just want to unmerge a single cell just click inside the cell, it is then selected automatically even though it is not highlighted.
2.Use the Unmerge tool in the Table tab or right-click and select Table > Unmerge in the context menu and then choose Rows, Columns or Rows and Columns.
Table Properties (Reference)
How table sizing works (Reference)