Teeth Question ( Gingivitis)?

Well I'm 14 years old and I went to the dentist today. I found out that I had a lot of tarter and I had gingivitis. I also have to get a filling on Jan 25. So first of all, how are you supposed to brush your gums. And second, I just bought a Philips Sonicare toothbrush, will this toothbrush help me remove my gingivitis?