You have to ensure that there are no gaps and spaces in the flooring and it is complete and perfect in every way.
How to place laminate flooring on stairs.
Once this is done measure and cut out your pieces of laminate to make tread pieces riser pieces and stair nosing.
The risers go on next.
However installing laminate flooring on your stairs is a completely different matter.
The riser must come flush with the surface of the tread and the stair nose which goes on last curls around the top of the riser and either fits flush against the laminate.
The international building code specifies a maximum riser height of 7 inches so a single laminate plank usually suffices but you may prefer to use pine poplar or some other stainable wood instead.
To install laminate flooring on stairs start by removing the overhang or the underside of the stairs with a jigsaw.
If you want to install laminate flooring on your stairs i would recommend that you do a lot of research and find the information you will need to do it correctly.
Alternatively you could cover the overhang with plywood to make it level.