You can save your Trees workspace to a disk using the Save As... command under the File menu. This may be useful if you want to come back to some partially completed trees later.
Note, however, that when you go to reopen a Trees workspace that you have saved, you should be sure to first choose again the grammar that you originally used to construct the tree.
Kind of obvious, really: use Print from the File menu. One thing you should note, though, is that you can save on paper by including multiple trees in a single workspace. Just be sure to organize the trees clearly.
Although the drawing window can be resized, it cannot be made wider than a sheet of standard letter paper. If you create the structure for a particularly large sentence, you may find that your tree is too large to fit in the drawing window at one time, and that it is too large to print on a single page. Before giving up in despair, there are some things that you can do to make your tree more compact. (i) Using the Size menu, set the font size to its smallest setting - 9 points, (ii) Using the Trees menu, select Drawing Preferences and select the narrowest width setting.