How to introduce our 12 month boy to out 8 week old girl

We have a 12 month old amstaff boy, we got a 9 week old amstaff girl last week and we are having troubles introducing him to her. We got our boy when he was 8 weeks old and a couple of weeks after that we had to leave Townsville to Brisbane as my son had a bad burns accident which left him in hospital for 3 months. We had to leave our boy in Townsville as we couldn't take him with us, he stayed with my partners friends where he grew up with 2 other female dogs. We had got him back in April this year, he kept getting out of our yard to try and be with the dogs next door. So we went and got a girl for him but he's just wanting to have a piece of her every time we try and introduce him to her. We have tried putting him on one side of a screen door on a lead and her on the other side, but he gets this deep grumbling growl and jumps up onto the door. Wanting a piece of her. There has been times when he is wagging his tail then he'll stop and then have a go at her again. Our next step is to take them to a park on leads and do it that way, we have got a mussel for him we're just a bit worried he'll hurt her. If you could give us any suggestions on how we can introduce them that would be appreciated.

Steve n Kylie

Have u tried walking your dog with an an older calmer dog firstly or socialisation classes?