Nenya is the Steward of Falkreach, unless there is something I am missing that makes Teckla the Steward.
Go talk to Nenya in Falkreach. She is the Steward. If it doesn't give you the option to buy property. Talk to the Jarl. He will send you on two quick quests and then grant you rights to buy property. That is when you talk to Nenya.
