(part. solved) anyone experienced in writing html code for login (esp8266)

hello,
anyone experienced in writing html code for login (username, password; esp8266) ?

I needed a function to retrieve 2 strings, 1 for username, and 1 for password, and if it's valid, then the standard website is loaded, otherwise the login website is stuck.
It should be very simple, just like this way:

"Enter username and password, then press [LOGIN] Button to submit:"

Username: [_________]

Password: [_________]

       [LOGIN]

edit - partially solved -
just understood the principle - by a html website one gets a long html string containing the single textfield strings....