1. Click "Edit" then click "Source" on the CKeditor toolbar, copy the source of the table code (with 3 columns and 50 rows) between the markers <!-- BEGIN TABLE --> and <!-- END TABLE -->
2. Click Source at your article, insert the code, then click 'Source" again to see if the table appears.
While in WYSIWYG mode, you can add/delete rows by right-clicking inside the table.