AS A Beginner What Do I Need To Buy (Learn) First?

Question

Hi,

I am a beginner and would like a beginners guidance.

I have had a program constructed with C# and built with .NET 2005 by a well informed programmer.

I have the source code and would like to examine it, but being just a beginner I know not where to start.

The programmer informed me of the following:

"The source code is in C# and built with .NET 2005 (but 2008 or 2003 should also work just fine).  Any programmer would need to know C# and SQL to make additions or modifications to this project."

My question is:
What do I need to buy  (in order to learn) and to view the source code of my project as described above. I am on a budget and need to make some changes to formulas.

Thanks for any help