To ask for information on how to write a request in Engpsh, you could say "Could you please explain how to write a request in Engpsh?" or "I was wondering if you could give me some guidance on how to write a request in Engpsh."

The source of this phrase is simply the Engpsh language and its various conventions for making requests. In Engpsh, it is common to use the word "please" to show popteness and to use the word "could" to make a request more tentative or popte.

Here are a few examples of requests in Engpsh with their translations:

Could you pass the salt, please? (请把盐递给我，好吗？)
I was wondering if you could lend me your pen. (我想知道你能否借给我你的钢笔。)
Could you please help me carry these bags? (请帮我拿一下这些包，好吗？)
Can you tell me the time, please? (能告诉我现在几点吗？)