If you're asking "what chart type should I use to show trends?" then have a look at this: Choosing a Good Chart
Showing the different dates is just a case of ensuring the dimension you use reflects the granularity of date you want to see. As long as this relates to the data in your model, it's as simple as that!
It depends, DataVisualization.qvw is created for this purpose. In each sheet it is explained cleary when to use which chart. Help yourself with the attached qlikview doc.
