Well you just Go to Format Picture go to the Layout tab and set the behind text option, alternatively if you have your text in a text box you can remove the default fill and border and float text on top of a GIF that way.
Admittedly It is a bit clunky as a DTP program because it is primarily a word processor and designed to deal with inline text and graphics by default. But if you change the format options of graphics and text boxes so they don't behave inline you can drag and drop things any where you want and arrange their order to, you can also flow text between text boxes and change their design to. So it's quite sophisticated and certainly can be used for DTP it's just not very intuitive to use and the default styles are not particularly helpful, so it can be fiddly to use and a bit frustrating on times.
Generally I prefer Corel Draw for most DTP type projects However I have used Word for designing Posters and flyers for people when I haven't had anything else to hand, it can be done :) Of course MS Word would be a lot better if it wasn't made by Microsoft :)