The graduation certificate and the transcript were put in the A4 sized enveloped and were given to the students on the graduation day, together with their diploma.
ご質問ありがとうございます。
"The graduation certificate and the transcript were put in the A4 sized enveloped"＝「卒業証書と成績表はA4サイズの封筒に入れられました」
"and were given to the students on the graduation day,"＝「そして学生たちに卒業式の日に渡されました」
"together with the their diploma."=「彼等の学位記と一緒に。」
ご参考に。
アメリカ合衆国 
