At your work station, secure each pine slat to the base with wood screws, then clamp together and to the work station. Work from one edge to the other.
Apply wood glue to each joint, clamp into final position, and drive in two wood screws into the previously made pilot holes. Continue along the length of the base, then do the same at the other ends of the pine slats, on the top bar.Step 6: Wood fill and sand
Apply wood filler to hole with an embedded wood screw, and allow to dry. Sand the dried wood filler smooth and sand down overall secured project again.