When you add a graphic to a document, you can either plop it straight in so it's stored in the document, or you can link the graphic so that the document just points to where the graphic is stored.
It looks the same either way, but here's the thing. When you email your document to someone, or post your template in a network directory, what happens to that link pointing to the graphic?
The link points back to your directory at home\documentdrafts\2008\graphics\teamphoto.gif or whatever the path is. And your cousin in Phoenix or the other people on your team can't get to that graphic.
So what you want to do, typically, when you're sending documents or templates to other people that those people need to work with, is to make sure that your graphics are embedded in your document.
NOTE: If you're doing large books or other documents where there are significant benefits to just linking to graphics, or if you have really big graphics of a few hundred KB or more, think hard before doing only embedded graphics. You'll have some issues, including really really big documents. Consider working with the documents only on the network so that the graphics are there on the network too and you don't have path issues. You might want to link as you work with the document, then if necessary break the links (see the last section here) or even better, make a PDF, before distributing the document.
How to Insert Graphics in Documents so They're Not Linked
When you drag a graphic from the Gallery (Tools > Gallery) into your document, it's automatically embedded. But when you choose Insert > Picture > From File, then you can choose to link or to not. If you want the graphic embedded, then don't select Link.
How to Add Graphics to the Background of Headers, Footers, or Pages So They're Not Linked
You can just click in a header or footer and choose Insert > Picture > From File. But you can also set up headers, footers, and pages with a graphic in the background.
Choose Format > Page.
Click the Header, Footer, or Background tab.
For Headers or Footers click the More.
Then you'll see this window. Select Graphic then click Browse. Find the graphic. Again, just be sure you don't click the Link checkbox which in this case is next to the Browse button.
How to Un-Link (Embed) Graphics When They're Already In Your Document
Let's say you've got a document chock full of linked documents and you reallllly don't want to re-insert them. It's easy to fix; just break the link and the graphics will be embedded.
Under the Edit menu, look at Links. If it's dimmed as shown, then you don't have any linked graphics and you're good.
If it's not dimmed, then choose Edit > Links. In the Edit Links window, just select the graphics listed and choose Break Link. The graphics stay, but now they're embedded and you can mail the document wherever you want or store it in another location.
(You could also select a graphic link and choose Modify to change where it's pointing to.)