Measure the stairs where your staircase turns and order the properly sized treads.
Lay the winding treads onto the stairs and fit them in place as you would a puzzle. Make sure the treads fit onto the stair perfectly with no gaps or overlap between the winding threads and other stair treads they are placed against. If there are gaps or overlap problems, the winding threads need to be ordered in the proper size to fit correctly.
Apply wood glue to the stair base. Run the ridged edge of the trowel over it.
Place the winding treads onto the stairs as you did in step 2. The treads will fit together like a puzzle with no gaps or overlap between each piece. Start against the wall and work out from there. Make sure each tread is pressed up against the tread next to it. Press the winding threads into the glue.
Allow the glue to dry for 12 to 24 hours before you use the stairs.