Gyro Autobalancing

[Luiz12]

Now from what I read, I know to tune the PID I must start with zero values on I and D and then adjust the PID until it begins to oscillate ( which I assumes means the robot) then divide it by half. (from what I read on wikipedia) but do I increase the P or decrease, and in what increments should increase by? It then says,"Then increase Ki until any offset is corrected in sufficient time for the process" which I really don't understand. Do I adjust this if I see any lag or what does it mean?