Priests and priestess here are dedicated to the worship of the goddess Mara, the goddess of Love. The Shrine of Mara within lessens the cost of Restorationspells by 10%.
In this temple, the Dragonborn can receive a quest series The Book of Love, involved with the romantic affairs of some of Skyrim's citizens, from Dinya Balu. The Dragonborn can also purchase an Amulet of Mara from Maramal which adds a 10% bonus to Restorationspells and allows the Dragonborn to marry certain citizens.
The first step is going to the Temple of Mara or The Bee and Barb inn. These are the two locations where the Maramal, priest of Mara, sells Amulets of Mara.
Once inside, talk to Maramal.
Chat about Mara and weddings, and he asks if the Dragonborn knows how marriage works in Skyrim. After an explanation, the Dragonborn can purchase an Amulet of Mara for 200 .
Wearing this amulet broadcasts to the other citizens that the Dragonborn is available. Locate a compatible citizen and speak with them. Some citizens cannot be married and others require that certain tasks be performed beforehand.
Travel back to the temple in Riften, tell the priest, and have a ceremony.
If you picked a common name for your character, a duplicate of your character may appear as a random pilgrim worshiping in the temple. Your doppelganger, if spoken to, may recite a word of power (similar to the Graybeards), nothing, or dialog from the priest of mara. It otherwise cannot be interacted with or targeted for any purpose.