How to update my theme?

Thank you for this module.
However I have one problem: I don't know in which file I should insert taxonomy_image_display($term->tid), or how to update my theme....

In the Install file it says:

Step 7)
Update your theme or other php code to display taxonomy images.

To display a taxonomy image from your theme or other php code, add
a call to taxonomy_image_display(). This function requires that you pass
in the term id of the term for which you wish to display the appropriate
image. For example:
taxonomy_image_display($term->tid)

Many thanks again :)
Expat9