Start with qlikview reference manual. Then there are many online trainings available here; keep visiting community. Then advanced ways would open up to you.
It may also be worth getting some manuals. I recommend:
QlikView 11 for Developers
QlikView Developers Cookbook
Both of which can be bought as a manual or E-book from Packt Publishing.
As Tresesco point out, have a go at answering questions on Qlik Community as this will show you some of the issues that can come up when looking at data. If you can't answer them, just follow the answers of other people to see how they would solve a problem.
