Select one or more cells.

Click Inspector in the toolbar and click the Table button.

In the Table inspector, click Format.

Choose Custom from the Cell Format pop-up menu.

The custom format window opens.

From the Type pop-up menu, choose Date & Time.

Define your date/time format by dragging the (blue) elements from the Date & Time Elements box into the format field above the box.

When an element is in the format field, click its disclosure triangle and choose a formatting option from the pop-up menu.

To display predefined text before or after any element, place an insertion point in the format field and then type your text. You can click any element and use the Left Arrow and Right Arrow keys to place the insertion point.

To display space between elements, place an insertion point and press the Space bar one or more times.

To delete an element in the field, select it and then press Delete.

To move an element around in the field, drag it.

In the Name field, type a name for your date/time format.

Custom format names are listed in the Cell Formats pop-up menu in the Format pane of the Table inspector.

Click OK to save your date/time format and apply it to the selected cells.