just did first battle

[Ancient Seraph]

You'll have to lead the target a bit (aim in front of it). Single player and/or Arcade are a good way to practice this, since in Arcade you'll see an indicator of where to aim to hit the target. You'll get a good idea where to aim after a while. Which 109 are you using? Some aircraft have more tracers, which makes it easier to aim, since you can see well where your bullets are going.