Where can you enchant items in oblivion

There are 2 ways. The first is to buy the official mod Wizard's Tower (of course, that costs REAL money), and the second, free way is to join the Mages Guild and get access to the Arcane University. You do that by doing 7 recommendation quests in the cities. There is one guild hall in each city (except the Imperial City), and you have to do a mission which you get from the leaders of the hall. Once you do all 7, you get access to the Arcane University in the Imperial City. There you find the Chironasium (i think) and use the Altar of Enchanting.
NOTE: If you need more help with the missions, visit www.gamefaqs.com and search for Oblivion.