virtualbox.org

HI,

I apologize in advance for my bad English...

I have Slax Linux on USB "www.slax.org/download/7.0.8/slax-Czech-7.0.8-i486.zip"

I tested the usb laptop and linux is booted slax (all successful)

I do not know how to boot linux slax from USB in VirtualBox...

As far as I can tell you can't. You would have to install Slax as a guest in VirtualBox.

Virtualbox doesn't yet support booting a guest from a bootable USB stick. You can get an ISO and boot from that instead.