Do you mean the 'Bogie the Ghost' badge? You won this on April 2nd, so well done!
You can see which badges you’ve won recently, by first clicking on the ‘Badges’ tab at the top of the home page. Then click on ‘My Collection’ and finally the link to ‘See all my earned badges’.
There’s occasionally a glitch where badges show as only part completed on the Home page, but don’t worry you have been awarded the badge.