Hi @Abdo. The simplest way is to try ti by yourself.
1) There are two kind of layers what you can add in Altium: "Layer" or "Plane".
- Layer is initially empty and you draw "cooper". In this case, nothing will happen on L2 and L3. In case you already have routed something in the space where you are placing the through hole VIA, just place the VIA into different location (with no wires on L2 & L3) or move the tracks on L2 / L3. If there is a polygon, Altium will automatically create a hole in the polygon (you may need to "Redraw" the polygons).
- Plane is initially full of copper. If you use a through hole VIA, Altium automatically creates a gap around the VIA on that layer (unless the VIA is connected to the same net as the plane).
2) Have a look at 3D View of the PCB. Maybe that can help? I attached it below.
I recommend you to have a look at our OpenRex design. You will understand immediately. You can download the full Altium projects of
OpenRex board >