To get started using NUnit, read the Quick Start page. This article demonstrates the development process with NUnit in the context of a C# banking application. Check the Samples page for additional examples, including some in VB.Net, J# and managed C++.
NUnit has two different ways to run your tests. The console runner, nunit-console.exe, is the fastest to launch, but is not interactive. The gui runner, nunit-gui.exe, is a Windows Forms application that allows you to work selectively with your tests and provides graphical feedback.