A planer comes into use when the woodworker intends to have flat boards of even thickness. Contemporary machines may have a planning platform that helps achieve accurate thickness more quickly. The woodworker adjusts the platform to set the cutting depth, then feeds the board through the machine. The in-feed roller carries the wood forward as it gets placed under the blades of the cutter drum before being moved out of the machine by the out-feed roller. Some planers have both manual and electronic controls.
Hardwoods come from deciduous, or broad-leaved trees, as opposed to softwoods, that are harvested from from evergreens. In general, the lumber derived from hardwood species are typically harder than softwoods, although there are exceptions (balsa wood is very light and soft, but is considered a hardwood). Most hardwood tree species lose their leaves in winter, and generally offer a much wider variety of colors and textures than softwoods. Typically, stock from hardwood species are a lot more expensive than those from softwoods.
Please read through the entire plan and all comments before beginning this project. It is also advisable to review the Getting Started Section. Take all necessary precautions to build safely and smartly. Work on a clean level surface, free of imperfections or debris. Always use straight boards. Check for square after each step. Always predrill holes before attaching with screws. Use glue with finish nails for a stronger hold. Wipe excess glue off bare wood for stained projects, as dried glue will not take stain. Be safe, have fun, and ask for help if you need it. Good luck!