Hi @Chenchao, cute pic!
As for your question, to create a new domain name you can go to any registrar website like Epik.com and simply type in the domain name you want. If it is available, you can buy it using credit card or paypal for around 8.5 USD
It seems you are very new in this industry.
With a question of "How to create a domain" sounds like you've never registered a name before.
May I suggest before registering a name that you read and study the forum for a while to learn what makes a good name.
There are many "opinions" on the forum of what is good and what is bad, but there is also great sound advice. And it's all free to learn!
You'll probably make some mistakes but read here to try and minimize those mistakes.
I think its good that beginners start with popular registrar and pay 10$ per domain because it limits the amount of bulls**t they can buy + they get to learn slowly.
VS easily buying 100 domains for 100$ only to realize its all sh*t and not being able to figure out why because there's too many.
Welcome @Chenchao - nice to have you at NamePros. As suggested above, it's a good idea to read a lot, buy a little, and be patient. Domaining is a slow process, so don't expect fast results.
To create a domain, you need to choose the best domain registration websites like domain.com, goDaddy.com, Namecheap.com, Bluehost.com etc. Then, Select your plan & contact with your hosting provider for other details.
Find 2-3 meaningless words in the cheapest extension you can find. Try sell it for thousands until you learn what a good domain actually is. Better still don't spend a cent till you know the answer to your own questions. A newbie is someone that has lost learning you can actually skip this part it if your pockets are not burning and dying to spend your money and just go professional when you know your ready. Sooner or later you will be able to spot a bargain.