Thank You Julia for the quick answer for your homework :) Please review the corrections given below:

1. I was upset. (very good)
2. I belived he. (I believe in him.) ( Is this what you mean?)
3. My English teacher ditention to Justin. ( Justin was given a detention from our English Teacher.)

POINTS TO IMPROVE ON:

Capitalization
Sentence Construction
Spelling

Enjoy your Thursday :)