After you click the print link at the bottom of the screen, you can say the number of pages to use when printing the family tree. You can experiment with various number of pages for the height and the width and preview your family tree as a PDF before you decide which one to print.
Once you have them printed, a paper cutter is nice to cut off the bottom and right margins, so that you can tape them together without gaps in the tree.
There are companies that will print out your family tree for you from your GEDCOM file. This resource lists a few of them toward the bottom of the page. Note that your GEDCOM file doesn't include pictures.
