My nord dragonborn will soon want to retire in Hjerim and get married. How do I do it?

Go to Riften. Talk to the priest Maramal at the Inn or at the Temple of Mara. He'll hook you up.

speak to maramal in riften at the inn if its your first time in the inn, then ask him for an amulet of mara (200 gold) and then equip it and find someone ask her if she/he is interested and then go back to maramal at the temple of mara and ask him if you can have a wedding then leave the temple wait till around 8pm then get married, after the wedding speak to your wife/husband and ask them were to live then you can have a 100 gold daily income from whoever you marry.