what to do next ?

This hacking tutorial teaches you the basics of how to hack, and those aren’t ever going to change. If you didn’t catch them the first time around, here they are again:

1. learn to program
2. learn how the internet works
3. learn how unix/linux works

Go download wireshark, nmap, hping, and a C IDE and just play around with all of them. That’s what the essence of hacking is; messing around with technologies until you find something cool. Check out my Hacking Facebook post and you’ll see exactly what I mean; it’s not really “hacking” as such, all I did there was peek into facebook’s code using firebug, and I found some cool stuff. But the hacking skills are the same. Some of you will want to ask “how do I download wireshark” or “how do I use hping” – you must understand that answering the question for yourself is half the point.
I also very definitely agree with R4di4tion’s suggestion to subscribe to bugtraq but I’d suggest signing up a new email account solely for it; it’s very high volume. You may also want to sign up to the security-basics, vuln-dev, web-application-security and pen-test lists. Reading the conversations that take place on those lists is a gold-mine of hacking information.