Measure out the length of the porch overhang with a measuring tape. Write down your measurements. Get the length for the front and sides of the porch.
Cut 2-by-4 boards to fit your measurements -- 2-by-4 boards are sold in standard lengths of 6, 8, 10 or 12 feet. Make a cut line on each board with a pencil and trim it to fit with a circular saw. If you have 6-foot long boards, and the porch is 10 feet wide, you would need two boards, one full length and one cut down to 4 feet in length.
Attach the boards to the overhang. Use a cordless screwdriver and wood screws. Place one screw every 8 to 12 inches horizontally. Screw the top of the board underneath the lip of the overhang.
Prime the new wood with an exterior latex primer. Brush on a thin coat of primer. If the wood grain still shows, add a second coat after allowing the first at least four hours to dry.
Paint the trim the desired color. Use a latex exterior paint. Brush it on over the primer and let it dry. Inspect the coverage. If you see a lot of brush marks or the coat is uneven, apply a second coat.