How do I find the houses?

[Enkidoh]

You mean guild housing? They're located in three new residential areas (one near each main city) - Mist near Limsa Lominsa, the Goblet near Ul'dah, and the Lavender Beds near Gridania. To open access to them you need to find an npc in a hamlet near each and complete a short and simple quest for each (the Ul'dah and Limsa ones are level 5 quests, with the npcs found in Scorpion's Crossing in Western Thanalan and the Red Rooster Stead in Lower La Noscea respectively, the Gridania one level 10 found in Bentbranch Meadows). This npc will then send you to speak to a guard at the zone line to the new residential area, who will explain about the housing system.

The zone line to the residential area will then be accessible (Ul'dah's one is a gate in Western Thanalan near the Eighty Sins of Sasamo, Limsa's one is a gate near the Red Rooster Stead in Lower La Noscea, and Gridania's one is a ferry at the Mirror Lake Docks south of Bentbranch Meadows). After doing this you have to enter the residential area, then after you've looked around to your heart's content, return to the quest giver to complete it.

From then on you can directly teleport to the residential area using the aethernet in the nearest city (for instance, you can teleport from the aetheryte in New Gridania directly to the Lavender Beds). Hope this helped!