Making application that works anywhere

Question

Hi guys! I made some simple win app using VS .net 2003 with C#. Everithing worked fine on my comp, but when I sent exe file to my friend, he couldnt run it. I suppose that he is missing DLL files that are needed. How can I find files that are needed to be included, and how to link them with the app using VS? Can he , after copying all that files run app if he doesn't have .NET framework installed on his computer? Thanks in advance!