i dont know how to install my TL-WN722N adapter
 

I am new to ubuntu. So i have installed ubuntu 8.10. Now I do not have an internet connection. I am using TL-WN722N as a wireless usb adapter. I would very much appreciate if someone teaches me how can I install my driver there with full steps.

Well, if you're new to Ubuntu and have just loaded 8.10, the best thing you could do is to stop now, and load the CURRENT version of Ubuntu, which is 13.04. Chances are that your device may 'just work', since 8.10 is fairly old, and support may have been added for it.

At the very least, you'll have a MUCH easier time loading new software/configuring things on a new version, than you would if you had old.

Well I had installed ubuntu 8.10 to help me first understand the basics of ubuntu. I am planning to install kali Linux after being familiar to Ubuntu. Can you please tell me the differences between Ubuntu 13.04 and Kali Linux or may be BackTrack? Or is Kali Linux just the upgraded version of Ubuntu 13.04?

Your adapter is supported by the ath9k driver. See this link

-->http://wireless.kernel.org/en/users/...9k_htc/devices

It will be in any up to date distro.

Ubuntu is a general purpose desktop system. Kali and Backtrack are penetration testing distros and are not intended for new users. You can go to www.distrowatch.com and find lots of information on the older Backtrack, or newer Kali.