How do I rotate text in Pages?

As there is no support for vertical text, the only way to rotate text in Pages is to use text boxes.

To do that, click once on the textbox, so it gets eight white diamonds to grab for resizing.

Then hold down the command key and hover the mouse over one of the diamonds. The mouse pointer turns into a bent double arrow, which you can use to rotate the text box.

To rotate in exact multiples of 45 degrees, hold down shift and command at the same time as you rotate.

If you want more precise control of the rotation, you can go to the Inspector > Metrics (the ruler symbol) and then type a value in the field for Angle.