Article in English: It's in Skyrim's south-east corner. You can fast-travel there by opening your map and selecting Riften.  If you haven't yet visited Riften, you can instead pay a horse-drawn carriage outside of Whiterun (in the stables) or one of the other major cities to take you there. You may already have an Amulet of Mara if you've explored a few of Skyrim's dungeons. Be sure to check for it in your inventory before proceeding. If you have done the "Book of Love" quest, you would also have gotten the amulet. From the entrance to the city, go left and straight. On the left there should be a large temple with stairs leading up to it. He's usually located in the Temple of Mara; if you arrive late at night, you may have to wait until noon or so the following day before he'll appear. If you still can't find him in the temple, he's most likely at the Bee and Bard pub, which is across the minor bridge in the middle of Riften. Maramal will respond by elaborating on Mara's lore. You can skip his dialogue by clicking the mouse button (or by pressing the A or X button on consoles). This will prompt Maramal to ask whether or not you're familiar with marriage in Skyrim. Maramal will explain how marriage works in Skyrim. This will require you to have at least 200 gold on you. As long as you can afford the amulet, Maramal will add it to your inventory. After doing so, you're ready to begin searching for a spouse.

Summary in Indonesian:
Pergilah ke Riften. Berjalanlah menuju Temple of Mara. Carilah Maramal dan berbicaralah dengannya. Pilih opsi "I wanted to know more about the Temple of Mara". Pilih opsi "I could have a wedding at the temple? Pilih opsi "No, not really". Pilih opsi "I'll buy an Amulet of Mara". Bawalah Amulet of Mara yang Anda beli.