1) you have to set the ISO/ASA value to be same as your camera. So if your camera setup is ISO400, you have to do the same to the flash.
2) I do not know the meaning of the blue and the red color but the value 1.4 2 2.8.. are the aperture value you need to set as equal to the camera setting.
In other word, put your camera in Av or manual mode. what you set on your camera, you just set it accordinly on the flash and shoot
On the other hand if you want to do flash compensation, like + 1 stop, just play with the apperture value on the flash. i.e if you camera use F2.8, you can set the flash setting to +1 stop at F4. This will give you +1 stop compensation