Blog Help

Alright, for all you bloggers out there, I could really use some technical advice.   I'm having trouble uploading a picture to my header.  I want to have a picture appear behind my title, like I've had in the past.  Recently, within the last few weeks, everytime I attempt to upload a picture to my header, it publishes way too big so you only see a portion of the picture.  I have had pictures upload there correctly in the past and I don't know what has changed, I've even attempted uploading the same pictures that once uploaded correctly, and they are messed up as well.

I go to Layout > Edit the appropriate header section > Upload from computer > and I click "Shrink to Fit" and "Picture Behind Blog Title"...and it comes out wrong. 

Anyone have any advice on how to fix this problem?  It's really annoying me!