How I go to China?

You have to apply for a China tourist visa to enter and visit China. First, you have to take part in a China tour group organized by a capable travel agency, since China embassy doesn't issue visa to individuall applicant for sightseeing purpose to China. You don't need to pay any visa fee to the China embassy, but you have to pay some service fee to the travel agency who help to process the visa for you.
You can see the required documents listed on this page https://www.travelchinaguide.com/embassy/pakistan.htm