What level are you having problems with?
To start with you'll need a C# programming environment. A common one
is Microsoft Visual Studio. I use Mono and NUnit since they are free.
Here's my compile/test script for the Macintosh:
cd ~/Documents/diff-match-patch/csharp/
rm DiffMatchPatchTest.dll
echo "Compiling..."
gmcs -t:library -r:System.Web.dll -r:nunit.framework.dll
DiffMatchPatchTest.cs DiffMatchPatch.cs
echo "...done."
read -n 1 -p "Press any key to continue..."
echo
nunit-console DiffMatchPatchTest.dll
read -n 1 -p "Press any key to continue..."
--
Neil Fraser
http://neil.fraser.name