You can print a current screen view of a family tree but it is not possible to print a view of your whole tree.
You can, however, gain a more detailed view of the tree to print by changing the tree view.
To change the Tree view, firstly select the tree you wish to view. (The option is at the top of the tree to change the view, for a more detailed view)
Select 'Family View'. The option to print your tree is at the top right side of your tree.