what can i do with back track ?

[511]

i mean simple things like hacking a zip file , hacking a wifi ..
ps : i'm using oracle virtual box , and it can't identify any wifi connection but it can connect to internet .. weird huh !

[Chris]

VirtualBox doesn't have direct access to your WiFi hardware by default; it connects to the internet using an internal network between your computer and the virtual computer.

Even if you switched, you can only hack WiFis if they use WEP encryption, and most people know by now that's unsafe and use WPA2 (which is pretty much unhackable).
You'd also need a special WiFi adapter, this doesn't work with the stock one in your laptop.