Step 5: Step 2a: lead bending & soldering - C1, C2, C3
Figure 1 is an illustration (x-ray view from front side of circuit board) of how the parts are to be arranged and wired together. Don't worry, we'll go through things step-by-step.
Start by wiring the ground leads of C1, C2, and C3 to pin 7 of the DIP socket. This will form a sort of "ground bus", anchor the capacitors, and get some of the wires out of the way. Then connect C1 to R1, C2 to R2, and C3 to R3 as shown schematically in Figure 2 and as seen from the rear side of the board in Figure 3.