|Since you have networking working you would not need networking advice.|
I have not played Age of Empires but multiuser lan games are pretty much the same.
In one of the game configuration screens is the option to play standalone or multiuser. If you choose multiuser you then have the option of creating a game [hosting] or connecting to a hosted game.
On the pc of your choice host the game. On the other pc join the game.
Pretty simple once you find the right screens.