I'm assuming your ward layer is a shapefile?
- Join data sets using a common attribute.
- Click into the symbology tab in the ward layer properties window.
- In categories, click Unique Values.
- In the Value Field dropdown menu select the data field you wish to display the values off, and click Add All Values.
- Click Ok.
You can then change the colours for different values to creat your theme map.
Hope this helps, Órla