Step 1: Make a Plan
To make this fort you can use my plan, or if you want, you can make your own similar idea. It makes it more fun when there is more than 1 floor.
Step 2: Gather Your Materials
For any good fort, you will need chairs and blankets. Books can help weigh down the blankets. You will also need a couch and sofa. The air mattress is optional, but makes the fort more comfortable. And something to watch movies on is great fun. I will be using my iPad. Lighting might be needed in some cases. A lantern should work. I also used safety pins to attach the sheets together.
Step 3: Setup
All you have to do for your setup is look at your fort floor plan, and make it with your furniture. Make sure you have enough room. That may mean moving extra furniture out of the way.
Step 4: Sheets and Blankets
First, cover the 2nd room/level with blankets so that no light can come in other than the couch. Next, take 2 sheets and attach them somehow so that they go lengthways. Do this twice. Now attach all the sheets together so that they make a big square like shape. Now cover the whole area with the square. Drape the edges over the chairs and couch, and weigh them down with books. Make the sheets as tight as possible to maximize the room inside. Finally, cover all of the open areas with thick blankets so there is no light coming in. Make sure to leave room for an entrance though. I put a window to the second room and put my iPad in between the chairs on the third picture. Have fun with your fort!