In general, I would say keep the top-side pour; it certainly does no harm, and it has some secondary benefits, such as less etching required and less thermal stress on the board during reflow.
You do still need to pay attention to current loops and place the vias appropriately, not just scattering them about randomly. Since the FT232R is the only active chip on the board, focus on its outputs. There are two LEDs that are powered by VUSB, and a few outputs associated with the serial port that are powered by VCC. Where do the currents flow when any of these outputs change state? Try to keep the paths as short and direct as possible.
Note in particular, the ground path for the USB connector in your non-pour example. It has to go down, cross below the chip, then come up on the right before it gets to the ground pins on the top of the chip. The top-side pour shortens this considerably. In either case, it would help if you adjusted the vias near pin 1 of the chip so that the bottom pour is continuous there.
One side point about your design: Try to avoid having three etches come together at an acute angle, like you have on your Vcc trace. Make that a right-angle tee connection.
The LM358 socket and the capacitors I put do not have holes. Only the resistors do.
You have selected an SMT footprint. Choose a through-hole footprint in the footprint association.
Why do the resistors have a yellow part (which a believe are the holes) and a red one (those that seem like parallelograms)? What are they?
The yellow part shows the (lack of) soldermask, which is where there will be exposed copper for you to solder to, while the red part is copper that is under soldermask.
Edit: correction. You have chosen the "Universal" resistor footprints, which are designed to be used with both through-hole and surface-mount resistors. Hence, they include pads in between the holes. The yellow simply indicates the "hole pads" which are on both sides of the board, while the red indicates the "surface" pads, which are only on one side.
If you're only going to be using through hole resistors, use footprints from the "Resistors_ThroughHole" library.
I need to put some pins in the board. For example, I need a pin to measure the OUT signal, and a pin to connect the circuit to VCC and GND. How can I insert these in the board?
You can either use test points and select an appropriate footprint, or you could use standard pin headers. KiCad provides a "Measurement_Points" footprint library that might be helpful if you go with the first option.
- ...I was expecting to see small circles with no copper on them to know where to use the drill and to make the process of hole-making easier. How can I make them appear?
The layer you have printed only shows the copper layers, which does not include the holes (holes are drilled through the copper layer by the board house, they don't care about holes in pads). If you want a hole in the middle, you can either modify the footprints to suit your needs, or try and combine the drill layer with the copper layer when you print.
However, you should be able to simply print the copper layer as shown, then print the drill layer and use that as a reference for where to drill.
Edit in response to further questions in comment:
I wanted to add some pin headers but I didn't know how. Should I add them in the schematic in Eeschema?
Add the pin headers in the schematic first, from the conn library. For example, if you wanted a 2x4 pin header, use CONN_02X04.
Then, go to the footprint association thing, and under Pin_Headers, select the appropriate footprint. In the case of the 2x4 pin header, you would use Pin_Header_Straight_2x04.
Then, regenerate the netlist, and pull in the updated netlist to the PCB editor.
I selected the only socket that was available having 8 pins. What do you mean then? I didn't understand.
For an LM358 socket, place the LM358 as usual, and select DIP-8_W7.76mm from Housings_DIP. DIP sockets have the same footprint as the chips they socket.
Best Answer
Even if you put a bit too much solder on the pad, or spill it, it won't matter. This is because of the solder mask, which is the (typically) green stuff you see on PCBs, although it can differ in colour.
On the pads of your components, you will notice a thin purple border, which indicates the solder mask is not to go there, leaving those copper pads exposed. You seem to have a few layers with similar colours, and I don't use KiCad, but on my package it is just called the solder resist layer.
So yes, the copper layer is just under the surface, as when it is manufactured, there will be a solder mask layer put on top, as well as any silk screen you have on there too.
There is nothing stopping you from putting a blob of solder between the resistor and the SOT23-5 pin, but I would place it close to the pad, and have a short trace connecting them.