DHTMLGoodies.com29. Glue to the Dowels and glue on the Newel - don't glue to the Liner29D.png
DHTMLGoodies.com30. Use a Divider to straighten the Newel30D.png
DHTMLGoodies.com31. Liners set in the stairhole - glue is not necessary.31D.png
This slideshow shows unfinished parts and an un-finished interior, but your interior should be completely finished before installing the Stairs and Landings, the Stairs should be painted, and the Landings should be at least first-coated before assembly.
Review the "Stairs" slideshow and the painting 'back-and-forth' on page 8 of the instructions (the exact sequence depends on your painting plan).