virtualbox.org

i can't find a way to get 256 color mode to work

i tried using a floppy disk

but there was no way to change the the VGA Card

can some one help me

i even looked up on the web and still can't find a way

You don't change hardware in a properties dialog, you change it in control panel and "Add new hardware".

Also, VGA is not a 256 color graphics card, VGA was 16 colors (4bpp).

If, rather than looking for a specific video mode, your question is how to get better graphics: install the Guest Additions (see chapter 4 in user manual).