1.Log in to your dashboard--> layout- -> Edit HTML
2.Click on "Expand Widget Templates"
3.Scroll down to where you see this:-
4.If you want to add image Before post title then add below code between above 2 lines.
Note : Remember to Replace "Your image URL here" with your real image URL.
After adding code, it look like below.
If you want to add image After post title then add the code like this.(after the above 2 lines)
5.Click on "Save Templates" and you are done.