Add image / delete icon to catalogue page

[jamescorp]

How do I add / delete images to the catalogue that are in the middle just under the standard header?

(white area under the header, between the left and right columns, above the shopping cart catalogue items)

 

At the moment on one page I've got a image of a man (oscommerce icon I presume) that I would like to delete.

 

Plus on another page I would like to add an image that stretches inbetween the left to right navbars under the header? (in the white section mentioned above)

 

Regards

James