You can try posting your answer here so I can help you correct :)

how to 不能放句首这样单独用。这是中式英文的习惯。 要加一个助动词。 how do you write an email .....

Start by greatings for example good morning.. good afternoon State the purpose of the email for example i'm interested in buying this brand of clothes.... And finish it up by greatings for example Best regards