Tabular Table Styling Help

Hi there, I’m have a difficult time trying to edit the style of the tabular table layout:

– how can I add a green checkmark into a cell?
-How can i style the top headers text separately -I would like the headers – Basic, Standard and Advanced the size they are now, but the text descriptions below need to be reduced in text size.
– Can I edit the background colors and text colors of the 3 heading rows?

Any help would be much appreciated!!

Mary