HELP

Tells us everything. Mods, which jarls who you talked to, what system, etc.

Dumb questions: Do you have it enabled? Did you buy it?

Some general rules: The people you need to talk to are Skald the Elder/Brina Merillis in Dawnstar, Nenya/Tekla of Falkreath, and Aslfur/Sorli the Builder of Morthal.

Furthermore, you needed to have complete specific quests. In Dawnstar, you need to complete both Waking Nightmare and Kill the Giant. Waking Nightmare is the Daedric Quest near Dawnstar. In Falkreath, you need to complete Kill the Bandit Leader. And in Morthal, you must complete Laid to Rest. Finally, you MUST have 5000 gold on you, or you can't buy the plot of land. They don't accept credit.

Couriers appear after level-up.

I've done all of that. Still no currior or option of purchasing land.

Again, what mods are you running? Or are you on a console?

Sweet cracker sandwich son, just make one topic. People will help, just be patient.

Also UESP can be your friend in terms of info, if you don't have a guide.