graphic button in drupal

I want to make a button on location on a php file that currently is just a hyperlink.
Currently, the code segment appear in a browser with the text "Donate now", but I want it to be a paypal button instead.

All this is part of a paypal module I have set up in Drupal. I have already figured out the proper way to use a .css file with this module to modify another aspect of it. And now I want to change the textual hyperlink to a paypal button.

The line of code in question looks like this in the paypal_donations_single.tpl.php file:

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