Switching firefox 1.0 users?

clicking on the firefox icon, i was recently asked which user i wanted to sign on as (i have never been asked this).. and i was forced to make a new username (one option was 'default,' which i couldn't choose, of course).... and now i have lost access to all of my bookmarked pages, as i am signed on with this new username, basically with a clean browser (no saved passwords, no history, no bookmarks).

i know there has to be someway to get to my old browser with all of my pw's, bookmarks, etc......but its frustruating me

so...
Q: how do i switch firefox users?. - thanks!!