You can create a static PayPal Donate button by adding the following code to your pages:

<form name="_xclick" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="user@yourdomain.com">
<input type="hidden" name="item_name" value="Customer Service">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="amount" value="10.00">
<input type="image" src="http://www.paypal.com/en_US/i/btn/btn_donate_LG.gif" border="0" name="submit" alt="Make payments with PayPal - it's fast, free and secure!">
</form>

This code shows the minimum information you need in order to create a Donate button. In the above example, the button is for $10.00 USD donation to Customer Service)