We never start a sentence with 'How to'.

Thank your remind.

thank u very much for your reminding

useful information.Studying

Thank you very much for your reminding.

应助达人

Thanks for your reminding！

happyjyl’s reminder is correct.

We should write:
“How do you open the box?”
“How can the box be opened?” etc.

On the other hand, during oral conversation face to face, we may say:
Do you know how to open this box?
Can anybody tell me how to open this box?

Under the oral conversation circumstance, we may omit the words in italic, i.e. how to open this box?

Forum is a place for people to communicate with written words, but in the style of conversation. Since the post may be considered as a form of “oral” conversation, starting a sentence with “How to” is acceptable.

Of course, when writing formal English, we should follow happyjyl’s advice.

Thanks to happyjyl’s reminder!

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Thank you for your kind reminder. I will pay attention to this kind of mistake.

应助达人

I have a question, if "How to" appears in beginning of headline, is it acceptable？

应助达人

Thank you very much for your reminding.