Your question is a bit ambiguous, I'm not sure if your exptecting some magic code that will create a game for you.
You'll need to learn the language, learn to deal with GUI, communication over networks etc. its all down to what you know but it will be the same as making any other application, type in your code, take out the errors etc.
gen1mx6 has a very good point though, java makes life simpler for that sort of thing