Must или had to?

l forgot to phone Sam yesterday. I _ phone him today
​

My school life is wonderful. there are three floors in my school and many new classrooms. there are a lot of computers which we can use. my dream is every classroom has ten and more new computers with internet.  there are lots of concerts, performances and sport competitions in our school. my classmates and i often take part in different school events. i have a lot of friends in my class.   our teachers are kind and intelligent and my classmates are smart and friendly. i like my school very much.