Tower Defence Minigame

ok first of all I need some one to help me figure out how to make a tower defence type game simulation, second of all..... I need to figure out how to put it into a minigame on my map. and lastly I want to make a reverse of the minigame for the player to do so that he is rushing the castle
EDIT: sorry If I sound demanding

DIY Steps:
1) Post SPECIFIC questions
2) Learn
3) Repeat steps 1 through 2 unti game is finished

Simple!

There are walkthroughs on the internet teaching you how to make TDs. Try the Hive Workshop... I think they have one there. How to put it into your map? I'm sure you can think of how to do that yourself... You need triggers and map space (obviously). You want a the roles to reverse after the TD minigame? You can figure that out yourself too. There is more than one way to do that. You can try changing the ownership of the towers to the opposing side o something... Oh yeah, someone wiser than I told be before that putting lots of extra stuff into the map tends to make the gamplay into.. erm.. soup. So be careful.

I believe you can look at the Skibi TD map and get a general idea of how they did mini-games.

Thanks for your comments