Do you want people to answer how to write postcards in English or do you want to translate the word postcard?

If it is a translation, it is a postcard.

How to write depends on whether you write a composition for the exam or communicate with people in reality. If you take the exam, you should write the address in the first line according to the format of the letter, wrap it up, and then write the content. If the content is there, the paper should be prompted. In the first sentence, you should say something like "How are you?", then translate the following contents according to the main points of the paper, and finally package it and write a blessing! Wrap the line again and sign.

If you communicate with others in reality, the format can be less formal, but greetings are very important. At least write Hi and Hello. I can't help you translate unless you enter the content. You'd better write your blessing at the end, be polite and sign your name. Don't forget to write the address on the address bar.