I'm sixteen and I get an erection daily during scool even kissing my girlfriend and I'm not a virgin I need help stoping these erections can anybody help?

You can't stop it. It is a normal physical reaction to intament contact.
If it is really bothering you, speak to your girlfriend about not kissing 'THAT' way any more. A simple kiss, a hug, etc, is more than effeciant to show affection

My boyfriend is 25 this year and it still happens to him, its very normal in young men, I have never even noticed until he actually tells me, but just wear loose trousers if your afraid someone will notice.