I assume that you mean that you need to see the Arabic layout because it's not on the computer's keyboard and you can't always remember it. As other people have said, if you have a keyboard switcher on the panel, it will
> show which script you are using
> change keyboards when you left-click on it
> give you the option of displaying the current layout on the screen when you right-click on it
Not all user interfaces have this available. AntiX usually comes with Icewm or JWM and I can't remember either having one. If you use Xfce, which is available for AntiX, that definitely does have one.
If you don't want to change GUIs, then another idea would be to save one of the images from here
http://en.wikipedia.org/wiki/Arabic_keyboard
Then you could display it on-screen with a picture viewer and keep it there all the time.
On the other hand, an on-screen keyboard can mean a display that you can use pick the letters with the mouse instead of typing. If you meant that, then there is this one wich you can install (use the instruction they give for Debian)
http://xmodulo.com/onscreen-virtual-keyboard-linux.html