Multiple treatments. I recommend careful brushing;not in and out but top down on upper teeth and bottom up on lower teeth.I suggest you floss 2 times a day.I also recommend you rinse your mouth with hydrogen peroxide after flossing.See a dentist.
Depends on severity. If mild can be cured w good brushing/flossing. See your dentist for instructions that are individualized for your problem...Make sure to clean between teeth daily. If gum pockets have formed or if gums receding will need comprehensive periodontal treatment. Your dentist may want to refer you to a periodontist (gum specialist) for rx.
Cleaning. Home care can remove plaque and improve burm health, if plaque hardens, a professional cleaning is necessary. See a dentist for an evaluation.