Using a Currency format

Here we will format the C column to use £ with commas and no decimal places.

Steps

1. Select column C by clicking on the column header C. You should see the column highlighted in grey with the green border.
   
   
2. Using the Number tab on the Excel ribbon, select the currency icon; if you click on the icon then the default currency is used, or if you click on the down arrow for the icon then you get to select which currency you want.

3. Select £ English from the options (or whichever currency you fancy using)
   
   
4. Use the Decrease Decimal icon to change the number of decimal places for the column being shown (to none) by clicking twice on the icon
   
   

Alternatively, you can right-click on the C column header and select Format Cells... to open up more options

This would allow you to select Currency Category; take note of the other Categories too - including Custom which can provide a variant of Currency and allows you to place the currency sign to beside the number rather than left-aligned; this option can also allow you to make numbers red when negative by using one of the samples provided on the popup.