So I am trying to learn about OOP, but I am stuck on interfaces. I understand what they are and what they are used for, but i am having problems actually IMPLEMENTING them. For example, I have a Collection class which I want to bind to a datagrid, which I can do using the IBindingList interface, but now I want to implement sorting and I am having a hard time finding good examples. All the "simple" examples I can find are good, but don't show how to implement sorting.

Does anybody know of a good website/book/etc. that tells all about interfaces and gives good examples?