It really depends on what you would like to do.
You could start with the free training QlikView provides.
Build your first QlikView is a good start. The QlikView Tutorial is also a decent. See the link below for both trainings.
In addition to Jacob's recommendation you can also download a free version of QlikView with a the Personal Edition licence. This enables you to play with the software at no cost.
QlikView's rapid deployment and delivery enables businesses to visually present information quickly and in a meaningful way. This can assist in identifying trends, provide comparative analysis, locating both associations and gaps in the data, and drill through the data for deeper analytical investigation.
As a reporting tool it is OK, certainly no better than it's competitors. But what gives it the edge is the ability to interact with the charts and change views.
With the free download you can have a good play.