I am using facebook login on my site. Everything is working using the facebook button. I would like to change the graphic image to be my own image. How can I change this?

I currently am using the following to display the button.

```
<fb:login-button v="2" size="medium" onlogin="FB_ConnectPostAuthorization()">Facebook</fb:login-button> 

```

Once again, all I want to change is the picture itself.