You should install version 2 of the software:
http://aminet.net/package/driver/video/Picasso96It comes with a manual which basically tells you that you need to adjust the settings for your monitor with the Picasso96Mode program and after that you need to change the screenmode to the gfx card with Prefs/Screenmode.
Regarding a gfx card on the Amiga, only system-friendly programs which support different screen modes will be able to run on the gfx card. Badly written hardware-banging programs (mostly games) will not work (they will still display on the native Amiga video output, if at all).
