So i saw that there was the house for sale in Windhelm and wanted to but it and figured out that to become a thane of Windhelm you have to finish the civil war questline, so i did, for the stormcloaks and became thane... But the Steward just says that theres been some un-pleasant-ness recently, so i finished the Main-Questline... Still Nothing. Can Anyone Help?

Have you done Blood on the Ice yet?

I may have... What is it?... Sorry for the inconvinence

Find the corpse on the grave after midnight. Should be a guard there to start the quest. That is the unpleasantness they mention to you.

Oh, Thanks Alot...

And to decorate it you need to complete the whole quest ( it comes in two parts, or one, depending on how you complete it )

And How much does it cost to decorate completly