Entering your Estate: Once you learn the Estate skill, presses H to open up the Mini House interface. Click on Enter Estate to go into your estate. Make a Title, decide whether to make it Private or not (if it is Private, you will need to put in a password only those who know the password will be able to get in to your estate), the number of users you want to be in your estate (max is 15), if you want items (Dream of Mirror Gold) in your estate to be private or not, and a notice that you want users to see when they enter your estate.
Click Ok to enter your estate! On the top-right of your screen will be your Estate info. It will show your name as the Room host, your Estate title, the amount of guests in your estate including yourself, your Notice, and the guests that are in your estate (they will be listed in the big scrollbox).
Click on the Wrench icon to edit the Estate Settings. Click on the icon underneath the wrench to Exit out of your estate. You will be teleported back to the map you were on before in Dream of Mirror. Click on the icon below the pencil icon to bring up the Item Decoration panel. If you bought furniture, you can right-click the furniture as it sits in your inventory slot to activate it and send it to the Item Decoration panel.
To get furniture into your estate, you need to go to the Furniture Shop Owner NPC in Roumen, Elderine, or Uruga and purchase any furniture you want.