Running LVS
From Vlsiwiki
To run LVS, you must have a schematic and a DRC clean layout.
Extract a schematic
In your layout, first perform extraction by selecting Verify->Extract. Select "Join nets with same name." This command will analyze all the electrical connectivity of the different layers and create an "extracted" schematic view. This is what is compared to your schematic.
Running LVS
To open the LVS window, select Verify->LVS... In this window, you will need to select both your schematic and the recently generated extracted schematic. You can do this by browsing and selecting the appropriate cell views.
Debugging errors
There is a separate wiki page, Debugging LVS, on suggestions for debugging errors. This is a very difficult problem sometimes, but it is usually a simple swap of nets or pins.