formal e-mail

Dear Bita teacher,

I hope you had a great weekend.

My name is SooJeong your student in 73 class. I'm writing to let you know that I apologize for the infornal e-mail that i sent before. And thank you for teaching me method of writing formal e-mail. Thaks to your teaching , I realized many things that I didn't know before. Thank you so much.
Thank you for your time.

Regards,
NamSooJeong.