I need help in logic of a game (modified tic tac toe) for a c++ project.?

I am doing a basic c++ course in my 1st year in coll and ive to make a project. im making a game, a modified tic tac toe. U have a 2*2 matrix(4 squares,each having 2 sides common). user has 3 stones and comp has 3 sticks. there are 8 edges of the matrix and 1 centre(making it 9 places to put stick or stone).user puts stick on 1 place, then comp puts 1 stone.when all sticks and stones are put,then user can move his stick 1 step along horizontal, vertical and if hes not on corner, also along a diagonal. similarly the comp can move 1 stone. the game finishes when either 3 sticks or 3 stones are lined up, either vertically, horizontally or diagonally. i need the logic for the best possible move for the comp to make. plz help!

I need help in logic of a game (modified tic tac toe) for a c++ project.?
http://erwnerve.tripod.com/tictactoe.htm