Buy the same wireless card I use here: http://ebay.to/1wfFAkk Alfa Networks AWUSO36H, NH, or NHA
Full verbal step by step tutorial on how to crack WEP encrypted passwords using aircrack-ng suit on Kali Linux.
If you are using VMware, Virtual box, or any Virtual application you will need to use an external USB WIFI card capable of packet injection. The WIFI card I use with and without my VMware is listed bellow.
My Wireless card: Alfa Networks AWUSO36NHA
you can buy this card online for around $25 - $40
You can buy one here: http://ebay.to/1wfFAkk
to check if your card can do packet injection after creating the monitor mode interface open a terminal and type in:
aireplay-ng -9 mon0
This will tell you your percentage of injection.
OR check out