I'm level 30 and still haven't revieved the message

You need to do the quest Laid to Rest.

Laid to Rest

here is a way to do the quest:

Go to the burnt house which is right of the Jarl's Longhouse. This triggers a topic added to the Morthal Guards.
Talk to the guards. They'll tell you to speak to the Jarl of Morthal, Idgarod Ravencone. Speak to her about the house and she'll tell you to investigate the burnt house.
When you're at the burnt house, you'll find a ghost girl by the name Helgi. She'll say she'll tell if you play hide and seek with her in the nighttime. At nighttime, go to the grave where her coffin is. There's also a vampire ready to attack so have your weapon out and then activate the coffin.
Then a guy comes by saying that she was his wife and that she was friends with Alva. He wants evidence that Alva is a vampire. Break into her house and go to the basement where there's a journal.
Give the journal to the Jarl. She'll read it saying that Alva burnt the house and a vampire named Movarth was behind all of this. Then she'll send you to his lair, which is a bit northeast of the town.
Go to Movarth's Lair, and then go inside, kill the vampires and Movarth himself and then talk to the Jarl. She'll reward you with a plot of land you can buy from the Steward.

The house is called Windstad Manor, with a feature of a fishing hatchery, where you can farm fish.