I have a Y510, but I suspect the software used will be similar.
To find a list of functions for the touchpad, go to start-> control panel -> mouse (it's listed under hardware and sound).
In the window that poped up, go to the last panel (device settings), and click on settings withSynaptics touchpad selected.
Here, you will get a list of the functions available to you from the touchpad. The scrolling effect is listed under "Virtual scrolling". Click on it to view its descriptions including instructions on operating it. Open up the tree to see more options such as increasing/decreasing the region that will activate the scrolling option.