When you run the game with this mod on, it will turn out you've inherited a mansion known as Frostcrag Spire. Its location is now marked on your map. Go there immediately and enter. The first thing you'll see will be the journal of a former owner. Read it to get the name of the shop that you'll be able to buy upgrades in: it's the Mystic Emporium in Imperial City Market District.
Talk to Aurelinwae and buy all expansion packages: Alchemy Lab, Bedroom Area, Library Area, and Vault Area. Buy two sets of Magetallow Candles as well (they're at the bottom of the list). The quest will be over - and you've just gotten yourself the coolest house in the game (even better than the other plug-in expansions). Go there and use the candles on both Altar of Enchanting and Altar of Spellmaking.
Now, what have we here? In the main hall there are two altars mentioned above, allowing you to create spells and enchant items. The central altar allows you to summon Atronachs - creatures that will serve and obey you. They don't have any time limit on them, so they'll keep existing until they are beaten in battle or dismissed by your will. You can choose to summon a Storm Atronach (3 Void Salts are required), a Flame Atronach (3 Fire Salts), or Frost Atronach (3 Frost Salts). You can issue commands to them by approaching and activating them. Then you get a dialog box allowing you to choose whether they should follow you, wait, or be dismissed. You can only own one Atronach at a time.
In the Living Area you'll see a huge botanical garden, an alchemist's paradise. Even the daedric plants are there, and they're almost impossible to find once you've cleared all the oblivion-based quests. The altar nearby fortifies your Alchemy skill by 15 points when you're near it, so keep close to it when you mix potions. There's also a balcony here that allows you to instantly teleport to any Mages Guild outpost in Cyrodiil, Arcane University included.
HINT: On a shelf in a cupboard near the bed there's a skill book on Alchemy: A Game At Dinner (screenshot on the left). A little more higher there's a Jewelry Box (screenshot on the right) containing a cool ring called Pentamagic Loop.
The Vault is a huge storage room in which you can leave your riches. There's also a rare wine collection that can come in handy in some quests.