Here is the template we used. You can find it if you google free standing trees, it should come up as one of the first websites, the website I used also included exact instructions on how to make and assemble the tree.
My tree is the one in the far corner closest to the box- I could not get a clear photo but you should hopefully get the idea.
All you have to do to make the tree is either print a copy of the tree template or draw one yourself, you have to do this so you have four copies, then stick the sides together until it resembles a free standing tree. Once you have created the base, cut leaves out of the coloured paper of your choice and sick them to each branch.