I'm new to modding and i was wondering if anyone could tell me if i can use the construction set that came with Morrowind on Oblivion

no - download the oblivion one

does it not come with the game of the year addition

Negative. D-load off the main page with the update.

http://www.elderscrolls.com/downloads/updates_utilities.htm

BTW, welcome to the forums.

Thanks