Trying to make an uneditable letterhead on Word 2010

[Brooksey123]

Hi all,

I've been having a problem trying to make an uneditable letterhead for my company.
I followed some advice that said to include the images and text in the header and footer. I then restricted editing in the header and footer, but because my image takes up space outside the header it means that no one else can write over where the image is.
I'm stuck on ideas on how to be able to write over the image.

I'm open to all ideas.

Thanks