Hi Daylene,
Is this the effect you're looking for? The image is of the top left quarter of the screen. The Numbers document has a single Sheet, containing a single 4 column by 10 row Table. The visible data are cell addresses of cells in the table. Cells whose address is not shown are empty.

The view below is of the same document, but with one of the table cells (B7) selected, making the table Active. Active tables show their cell grid, and show the column and row Reference tabs.

The example started with a Plain style table no Header rows or columns). Cell borders were set in a few steps:
- Select the whole table
- Open the Table Inspector

- Click the 'outside borders' button (highlighted) in the Cell Borders section.
- Set the stroke thickness to None.
- Click the 'inside borders' button (immediately left of the highlighted one above)
- Set the stroke thickness to None.
Apple delivers a couple of excellent resources with the iWork applications—download links for each application's User Guide and for the iWork Formulas and Functions User Guide.
You'll find the link for the Numbers '09 User Guide in the Help menu in Numbers.
A search on 'cell border' should take you to an appropriate page, containing the article referenced in my reply above.
Reading the first few chapters of the Numbers '09 User Guide will also introduce you to Header Rows, Header Columns and Footer columns, the first two of which are likely what you're referring to as "the side and top bars." Cells in these rows have useful properties not shared with the 'regular' cells in the body of a table. You can have a 'plain' table without these rows (eg. the one in my example above).
Regards,
Barry