Have 'recent posts' display as image only

https://www.bonnetsinwonderland.com (twenty twelve theme)

I’d like to have ‘recent posts’ on Main Sidebar display as an image rather than a title. I have read through past posts, but some seem dated. Checking in here, if anyone has a suggestion.

Thank you!

PS – if you happen to know how to change the setting so that entries on my about page dont list under ‘recent posts’ as a three-digit number, that would be helpful also:)