I was creating a pcb board that is mostly made of header pins that are suppose to connect to adapters. I was wondering if a stencil is required for soldering through hole components on a bare bone pcb.
This depends on the technology you're using for soldering the through-hole parts. If you're hand-soldering them then no, you do not need a stencil. However, if you are using paste-in-hole technology (aka "intrusive soldering") then you might. There are a number of different ways to apply paste for intrusive soldering and if you do it by hand (use a syringe to apply the paste in and around the hole) then no stencil is required. Otherwise if the application of paste is automated, you probably will need a stencil. Note you may need a separate, thicker stencil for applying paste for intrusive soldering due to the larger amount of paste required for through-hole soldering versus surface mount.