Anyone can say how could make a connection between HTML document and database?

Answer 1

So you'll need to learn php.
When hosting a website you can either host a static HTML website or you can use a wonderful language called php to save a user's data, make things more interactive with the user, do complicated server side calculations like encryption and decryption and a lot more!

You can start learning the basics of php here on Sololearn.
Enjoy!

Answer 2

PHP

Answer 3

very soon learn php