Just had a quick look at Blogger and:
To add the social networks tool bar:
Edit the Layout and on 'Page Elements' tab click 'add a gadget' where you want to add the social networks gadget.
Click on 'Featured' and scroll down to 'Sociable Add ' (or search for Sociable Add is easier) then click the big + sign
Set a title and height and then click save, you now have a widget for social networking sites..
Adding an image is much more tricky, I think you are asking how to add an image as a link in the menu, and as far as I know you cannot do this with Blogger.
You can add images to the Header, as you have done, and to posts. Again as you have done.
To add a clickable image would require you to make a gadget that uses the image, and a link, but will need to be hosted on the web somewhere..