Select the image, then click on the Ribbon’s "Format Picture" tab, then "Wrap Text" (in the Arrange group). The highlighted option will reflect whichever wrap format you're using. For a visual description, see:
http://www.dummies.com/software/micr...-2011-for-mac/
If the wrap format is anything other than 'In line with text', merely clicking on the image will probably be sufficient to display an anchor symbol showing what the image is anchored to.