Subscribe2: how to personalize subscription page

When you install Subscribe2 you create a page & add a ‘subscribe2’ tag to the page.

I would like to customize this page so that in addition to the default text I could add a msg. telling people they may also subscribe to individual categories by first registering & choosing which categories they’d like to subscirbe to.

Should I add this msg. directly into the Subscribe2 page or does it have to go into a subscribe2 file on my server?