how do I make a test project for an existing solution?

Question

how do I make a test project for an existing solution?

I have jumped on board a new project and a new job. We are doing windows embedded software development with a multi-project solution.

I did some development on one class in one project.

Now I want to test my work by using a separate project. How do I do that?

I am using Visual Studio 2008 and Visual Studio 2010. Should I use some other tool in addition? The Microsoft Windows Dev Center forums mentions the following sub-catagories:

Test Tools in Visual Studio 2010 and 2012
Testing with Visual Studio Test Manager (MTM)
Visual Studio Unit Testingsti

Should I use these tools instead of just adding a new command line visual studio project?