我现在在上高1 用英文怎么说

I'm a Senior High School student and i am in grade one.

I am a grade one student of senior high school.
这句话用 我是高中一年级的学生 这种说法比较好

I am in Grade One of high school.(在美国，high school就是高中）

I am in senior high school,Grade One now.

I am in senior high school,Grade One

I am in Grade one now。