IZennoList - it is interface to work with separate list. Represents the data of the list. Provides methodы to work with this particular list
ILists - it's the inteface to get separate list by it's name. After that we can use methods provided by IZennoList interface
Lists - It's a property of "project"
if you ask this and mean "How to use list objects" then you type project.Lists["MyList"]. and all possible methods will be presented. No other option for this.
If you're curious what's the difference between object, method, interface, property, i suggest you to read any book about C#