We make lot of dens in our house, actually not so many made by me anymore, tends to be Hebe who is the champion den builder now. She utilises every chair, stool and sofa and often incorporates shelves (tucking blankets under the toy boxes on the shelves) into her den designs.
This is a view of her that is so familiar. We even have special den building blankets.
Father Christmas obviously knew of her like of den building, and brought her this A frame tent which she now adds onto her dens.
FC must have the got the instructions to make the tent from this great tutorial here. The tents are very easy to make, the only adjustment
I , I mean father Christmas made was to staple a piece of fabric tape between the uprights to stop the tent splaying out and collapsing. Another little tweak is that you really need some sort of cap end to go on the end of the dowelling so it does not slide out of the uprights, at the moment we are using hair bobbles as you can see in the bottom left of the above picture.
This is my Den Envy page on Pinterest where I have pinned some great den inspiration.