How to get an ex back???????????????????

ok so me and my ex dated lats year for 7 months broke up and then went out again for 2months. we are both in 10th grade going to 11th. from the last time we have gotten into mulitple fights and hated and talk **** about each other. recently we have deicided to be friends talk and be close again btu he has a gf. ik ur probably going to say im to young to know wht love is but i really do think i love him. even though many pp say we shouldnt be together im happy being with him and i really just want him back but hes gf? plz help!!!!!!!!!!!!