Measure the space where the bookshelf will go
Decide the bookshelf height, width, and depth
Choose the material for the frame and shelves
Gather tools, fasteners, glue, and finishing supplies
Cut the side panels, top, bottom, shelves, and back panel to size
Sand all cut edges and surfaces
Mark shelf positions on the side panels
Drill pilot holes for shelf supports or screws
Assemble the frame with glue and screws or nails
Install the shelves at the marked positions
Attach the back panel to square the structure
Check that the bookshelf is level and square
Fill screw holes and sand the surface again
Apply paint, stain, or sealant
Let the finish dry completely
Move the bookshelf into place
Anchor the bookshelf to the wall if needed