Creating a Pie chart in numbers

When you're not quite sure how to do something it can be helpful to study working examples. Don't forget to check the excellent examples in the built-in templates at File > New on the Mac or in the Choose a Template area on the iPad. There is one called 'Charting Basics.' Go to the 'Pie Charts' sheet and you will see this.

Also see this entry in the User Guide (which you can also access via Help > Numbers Help in your menu):

Add column, bar, line, area, pie, doughnut and radar charts in Numbers on Mac - Apple Support

SG

Create a new table with one header and one footer row:

Choose the top left table:

Now add some data:

Now choose the values:

Now add a Pie chart from the Charts Tool menu (bottom left of the menu in the screenshot):

Wayne has got the steps covered - highlight a selection of cells, and click ont he item in the menu bar at the top to create a chart, and select the one that looks like a pie chart.... simple.